Midterm 1

Question 1

50) A train starts from rest and accelerates uniformly until it has traveled 2.1 km and acquired a forward velocity of 24 m/s. The train then moves at a constant velocity of for 400 s. The train then slows down uniformly at 0.065 deceleration until it is brought to a halt. The distance traveled by the train while slowing down is closest to
A) 4.4 km.
B) 4.2 km.
C) 4.0 km.
D) 3.8 km.
E) 3.6 km.

Answer 1

Answer A) 4.4 km

v^2 = u^2 +2*a*x

v=0
u^2/2a=x
x=24^2/2*0.065
x=4430.8= 4.4 km

Question 2

49) A train starts from rest and accelerates uniformly until it has traveled 5.6 km and acquired a forward velocity of 42 m/s. The train then moves at a constant velocity of for 420 s. The train then slows down uniformly at until it is brought to a halt. The acceleration during the first 5.6 km of travel is closest to which of the following?
A) 0.16 m/s
B) 0.14 m/s
C) 0.17 m/s
D) 0.19 m/s
E) 0.20 m/s

Answer 2

v^2=u^2+2(a)(s)

42^2=0 + 2a x 5600

a=0.1575=0.16

Answer A)

Question 3

48) At the instant a traffic light turns green, a car that has been waiting at the intersection starts ahead with a constant acceleration of 2.00 m/s2. At that moment a truck traveling with a constant velocity of 15.0 m/s overtakes and passes the car.
(a) Calculate the time necessary for the car to reach the truck.
(b) Calculate the distance beyond the traffic light that the car will pass the truck.
(c) Determine the speed of the car when it passes the truck.

Answer 3

a) S= Ut + 1/2 at^2
15t=0 + 1/2 (2)(t^2)
15t=t^2
t= 15 seconds

b) distance= time x speed
15 x 15= 225 meters

c) v= u+at
v= 0 + (2 x 15)
v= 30 m/s

Question 4

47) A car travels at 15 m/s for 10 s. It then speeds up with a constant acceleration of 2.0 m/s2 for 15 s. At the end of this time, what is its velocity?
A) 15 m/s
B) 30 m/s
C) 45 m/s
D) 375 m/s

Answer 4

C) 45 m/s
2 x 15= 30 m/s
30+15= 45m/s

Question 5

46) A certain test car can go from rest to 32.0 m/s in 3.88 s. The same car can come to a full stop from that speed in 4.14 s. What is the ratio of the magnitude of the starting acceleration to the
stopping acceleration?
A) 0.937
B) 1.07
C) 0.878
D) 1.14

Answer 5

Answer: B 1.07
In the first case,

Final velocity (v)=32 m/s

Initial velocity (u)=0 m/s

time (t)=3.88 s

Acceleration =a

Using the following equation of motion,

v=u+at

32=0+(a×3.88)

a=(32/3.88)=8.247 m/s2

In the second case,

final velocity (v)=0 m/s

Initial velocity =32 m/s

time (t)=4.14 s

v=u+at

0=32+(a×4.14)

a=(-32/4.14)=-7.729 m/s2

(Negative sign indicates the decreasing speed )

Ratio of magnitudes of starting acceleration to the stopping acceleration is,

(8.247/7.729)=1.07

Question 6

45) An auto accelerates forward from 7.0 m/s at a uniform 0.71 m/s2. It travels a distance of 1.033 km while accelerating.
(a) How fast is the auto moving just as it is traveled the 1.033 km?
(b) How many seconds did it take to travel the 1.033 km?

Answer 6

Question 7

44) A water rocket can reach a speed of 75 m/s in 0.050 seconds from launch. What is its average acceleration?

Answer 7

70/.050= 1500

Question 8

43) Arthur and Betty start walking toward each other when they are 100 m apart. Arthur has a speed of 3.0 m/s and Betty has a speed of 2.0 m/s. How long does it take for them to meet?

Answer 8

total velocity= 3m/s + 2m/s= 5m/s

time= displacement/velocity

100/5= 20seconds

Question 9

A Ferris wheel has radius 5.0 m and makes one revolution every 8.0 s with uniform rotation. A person who normally weighs 670 N is sitting on one of the benches attached at the rim of the wheel. What is the apparent weight (the normal force exerted on her by the bench) of the person as she passes through the highest point of her motion?

Answer 9

R = 5m , T = 8sec weight =670N

V = ω × R

V = (2π/(8))×R

V = 3.928m/s

M = 670/(9.8) = 68.367kg

W_app = W + Mv²/R

W_app = 670 + ((68.367)(3.928)²/(5))

W_app = 880N (approx.)

Question 10

4) Convert 1.2 × 10-3 to decimal notation.

Answer 10

D.

10^-3 means move decimal left 3 places = 0.0012

Question 11

8) The number 0.003010 has

Answer 11

C) 4 significant figures.

0.003010leading zeros do not count

Question 12

7) 0.00325 × 10-8 cm can also be expressed in mm as

Answer 12

C) 3.25 × 10-10 mm. (1cm = 10mm) 0.00325 × 10-8 = 0.325 × 10-11

Question 13

6) 0.0001776 can also be expressed as

Answer 13

B. 1.776 × 10-4.

Question 14

3) The current definition of the standard kilogram of mass is based on

Answer 14

C.

the mass a particular object kept in France (Le Grand K)

Question 15

2) The current definition of the standard second of time is based on

Answer 15

A.

the frequency of radiation emitted by cesium atoms (cesium-133 clock)

Question 16

1)The current definition of the standard meter of length is based on

Answer 16

C.

distance traveled by light in a vacuum = 1/299,792,458 of a second.

Question 17

67) A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock’s motion are true just before it hits the ground? (There could be more than one correct choice.)

A) Its horizontal velocity component is zero.
B) Its velocity is vertical.
C) Its vertical velocity component is the same as it was just as it was launched.
D) Its horizontal velocity component is the same as it was just as it was launched.
E) Its speed is the same as it was just as it was launched.

Answer 17

D)Its horizontal velocity component is the same as it was just as it was launched.

a=0 in the X direction so object maintains its horizontal velocity component from launch

Question 18

42) If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery in 2.00 hours, what is your
(a) average speed?
(b) average velocity?

Answer 18

Speed = distance/time

4+4+2.5/2= 5.25 km/h

average velocity= displacement/time

2.5/2=1.25 km/h

Question 19

41) A bat, flying toward the east at 2.0 m/s, emits a shriek that is reflected back to it from a wall that is 20.0 m in front of the bat at the instant the shriek is emitted. Sound travels at 340 m/s in the air. How many milliseconds after emitting the shriek does the bat hear the reflected echo from the wall?

Answer 19

117 milliseconds

20 x 2= 40 meters

40/340= 0.117 seconds= 117 milliseconds

Question 20

40) If you are driving 72 km/h along a straight road and you look to the side for 4.0 s, how far do you travel during this inattentive period?

A) 18 m

B) 20 m

C) 40 m

D) 80 m

Answer 20

D) 80 m

72 km/hr x 1000/3600= 20 m/s

20 x 4= 80meters

Question 21

68) You are trying to cross a river that flows toward the south with a strong current. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat
A) directly toward the west.
B) directly toward the north.
C) in a general southwesterly direction.
D) in a general northwesterly direction.

Answer 21

D) in a general northwesterly direction.

Question 22

69) You push on box G that is next to box H, causing both boxes to slide along the floor, as shown in the figure. The reaction force to your push is:

A) the push of box G on box H.
B) the push of box H on box G.
C) the push of box G against you.
D) the upward force of the floor

Answer 22

C) the push of box G against you.
Newton’s Third Law

Question 23

60) For general projectile motion with no air resistance, the horizontal component of a projectile’s acceleration

A) is always zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) first decreases and then increases.

Answer 23

A) is always zero.

Question 24

59) For general projectile motion with no air resistance, the horizontal component of a projectile’s velocity

A) remains zero.

B) remains a non-zero constant.

C) continuously increases.

D) continuously decreases.

E) first decreases and then increases.

Answer 24

B) remains a non-zero constant.

Question 25

58) If A + B= C and their magnitudes are given by A + B = C, then the vectors and are oriented.

A) perpendicular relative to one other.

B) parallel to each other (in the same direction).

C) antiparallel to each other (in opposite directions).

D) It is impossible to know from the given information.

Answer 25

B) parallel to each other (in the same direction).

Question 26

57) Two displacement vectors have magnitudes of 5.0 m and 7.0 m, respectively. If these two vectors are added together, the magnitude of the sum

A) is equal to 2.0 m.

B) could be as small as 2.0 m or as large as 12 m.

C) is equal to 12 m.

D) is equal to 8.6 m.

Answer 26

B) could be as small as 2.0 m or as large as 12 m.

7-5=2

7+5=12

Question 27

56) A bullet shot straight up returns to its starting point in 10 s. What is the initial speed of the bullet, assuming negligible air resistance?

A) 9.8 m/s B) 25 m/s C) 49 m/s D) 98 m/s

Answer 27

Vf= Vi + at

t= 10/2= 5

0= Vi + (-9.8)(5)

Vi= 49 m/s

Question 28

55) A hammer is thrown upward with a speed of 14 m/s on the surface of planet X where the acceleration due to gravity is 3.5 m/s2 and there is no atmosphere. What is the speed of the hammer after 8.0 s?

A) 7.0 m/s B) 14 m/s C) 21 m/s D) 64 m/s

Answer 28

The speed of the hammer is

V= Vi - at= 14-28= -14 m/s

acceleration absolute value= 14m/s

Question 29

54) An astronaut on a strange new planet having no atmosphere finds that she can jump up to a maximum height of 27 m when her initial upward speed is 6.0 m/s. What is the magnitude of the acceleration due to gravity on the planet?

Answer 29

maximum height Hmax = u^2/(2*g)

27 = 6^2/(2*g)

2*g = 36/27 = 1.33

accelaration due to gravity is g = 1.33/2 = 0.66 m/s^2

Question 30

53) A stone is thrown with an initial upward velocity of 7.0 m/s and experiences negligible air resistance. If we take upward as the positive direction, what is the velocity of the stone after 0.50 s?

A) 2.1 m/s B) 4.9 m/s C) -2.1 m/s D) -4.9 m/s E) 0.00 m/s

Answer 30

v = u+at

v = 7-9.8*0.5

v = 2.1 m/s

Question 31

52) Acceleration is sometimes expressed in multiples of g, where 9.82 is the acceleration of an object due to the earth’s gravity. In a car crash, the car’s forward velocity may go from 29 m/s to 0 m/s in 0.15 seconds. How many g’s are experienced, on average, by the driver?

Answer 31

v = u + a * t

0 = 30 + a * 0.15

a = - 200 m/s^2

the number of g’s , n = |a| /g

n = 200 /10 g = 20 g

Question 32

51) A soccer ball is released from rest at the top of a grassy incline. After 6.4 seconds the ball has rolled 91 m with constant acceleration, and 1.0 s later it reaches the bottom of the incline.
(a) What was the ball’s acceleration?
(b) How long was the incline?

Answer 32

a) S= ½at^2

91= ½ a (6.4)^2

a= 91 x 2/40.96= 4.4

b) S= ½ (4.4) (6.4 + 1)^2= 120.47= 120 meters

Question 33

101) A wind farm generator uses a two-bladed propeller mounted on a pylon at a height of 20 m, as shown in the figure. The width of the pylon is very narrow, and the length of each propeller blade is 12 m. A tip of the propeller breaks off just when the propeller is vertical. The fragment flies off horizontally, falls, and strikes the ground at point P with negligible air resistance. Just before the fragment broke off, the propeller was turning uniformly, taking 1.2 s for each rotation. How far is point P from the base of the pylon?

A) 120 m B) 130 m C) 140 m D) 150 m E) 160 m

Answer 33

E) 160

Question 34

5) Write out the number 7.35 × 10-5 in full with a decimal point and correct number of zeros.

Answer 34

B.

10^-5 mean move decimal 5 places left = 0.0000735

Question 35

70) A small car and a large SUV are at a stoplight. The car has a mass equal to half that of the SUV, and the SUV can produce a maximum accelerating force equal to twice that of the car. When the light turns green, both drivers push their accelerators to the floor at the same time.

Which vehicle pulls ahead of the other vehicle after a few seconds?
A) The car pulls ahead.
B) The SUV pulls ahead.
C) It is a tie.

Answer 35

C) It is a tie.
Initial V = 0 for both

F =ma
F(car)=1/2m a
F(suv)= m a
2F(car) = F(suv)
2F(car)= 1/2 m a (2 cancels out the half)
They become equal at least for the first few seconds

Question 36

8) The number 0.003010 has

Answer 36

C) 4 significant figures.

Question 37

9) What is to the proper number of significant figures in 0.674/0.74

Answer 37

A.

0. 91
   (0. 74 only has 2 sig figs and determines sig figs for the answer)

Question 38

71)A velocity vector has components 36 m/s westward and 22 m/s northward. What are the magnitude and direction of this vector?

Answer 38

Answer: 42 m/s at 31° north of west

Question 39

72) When rolled down a mountainside at 7.0 m/s, the horizontal component of its velocity vector was 1.8 m/s. What was the angle of the mountain surface above the horizontal?
A) 75°
B) 57 °
C) 33°
D) 15°

Answer 39

A) 75°

Angle = cos^-1 (1.8/7) = 75

Question 40

Kepler’s Third Law for a Circular Orbit Equation

Answer 40

Question 41

The speed of a satellite is the distance traveled during one period and is calculated by the following:

Answer 41

Question 42

10) What is the sum of 1.53 + 2.786 + 3.3 written with the correct number of significant figures?

Answer 42

B. 7.6

(3.3 only has 2 sig figs and determines sig figs for the answer)

Question 43

11) What is the product of 11.24 and 1.95 written with the correct number of significant figures?

Answer 43

B.

21.9 (1.95 has 3 sig figs and determines sig figs for the answer)

Question 44

73) When Jeff ran up a hill at 7.0 m/s, the horizontal component of his velocity vector was 5.1 m/s. What was the vertical component of Jeff’s velocity?
A) 4.8 m/s
B) 4.3 m/s
C) 3.8 m/s
D) 3.4 m/s

Answer 44

A) 4.8 m/s

Use Pythagorean Theorem to calculate Y component of vector

Question 45

12) Express (4.3 × 106)-1/2 in scientific notation.

Answer 45

A.

4.8 × 10-4 (-½ power is = 1/x^-2)

(-2 power = square root)

Question 46

13) The length and width of a rectangle are 1.125 m and 0.606 m, respectively. Multiplying, your calculator gives the product as 0.68175. Rounding properly to the correct number of significant figures, the area should be written as

Answer 46

C.

0.682 m² (least sig figs is 0.606 with 3 sig figs)

Question 47

14) The following exact conversion equivalents are given: 1 m = 100 cm , 1 in = 2.54 cm, and 1ft = 12 in. If a computer screen has an area of 1.27 ft², this area is closest to

Answer 47

C) 0.118 m² ( 1.27 ft² ) (144in²/1ft²) (6.45cm²/1in²) (1m²/10000cm²)

Question 48

15) In addition to 1 m = 39.37 in

If a particle has a velocity of 8.4 miles per hour,its velocity, in m/s, is closest to

(1mile = 5280ft, 1ft = 12in, 1 hr = 60min, 1min = 60sec)

Answer 48

A) 3.8 m/s. ( 8.4 mile/hr) (5280ft/1mile)(12in/1 ft)(1m/39.97in) = 13315.6 m/hr

13315.6m/hr (1hr/60min)(1min/60 sec) = ~ 3.8m/s pro tip: 1 hr = 3600 seconds

Question 49

16) A weight lifter can bench press 171 kg How many milligrams (mg) is this?

Answer 49

A) 1.71 × 10⁸ mg (171kg) (1000g/kg)(1000mg/1g) or (1.71x10²)(1x10⁶)

Question 50

17) How many nanoseconds does it take for a computer to perform one calculation if it performs 6.7x10⁷ calculations per second?

Answer 50

A) 15 ns 1 sec/6.7x10⁷calc = 1.5x10^-8 sec/1calc.

(1 sec = 1x10^-9 nano sec)

Question 51

18) The shortest wavelength of visible light is approximately 400 nm. Express this wavelength in centimeters.

Answer 51

A) 4 × 10^-5 cm (400nm = 400x10^-9m or 4x10^-7m)

4x10^-7m (100 cm/1m)

Question 52

19) Convert a speed of 4.50 km/h to units of ft/min. (1.00 m = 3.28 ft)

Answer 52

D) 246 ft/min 4.5km/hr = (4500m/hr)(3.28 ft/1m) = 14760ft/hr(1hr/60min)

Question 53

20) Which of the following quantities has units of a displacement? (There could be more than one correct choice.)

A) 32 ft/s2 vertically downward

B) 40 km southwest

C) 9.8 m/s2

D) -120 m/s

E) 186,000 mi

Answer 53

B and E

(units of displacement involve a magnitude of distance covered only)

C and A ) are units of acceleration

D) is a unit of velocity

Question 54

21) When is the average velocity of an object equal to the instantaneous velocity?

Answer 54

C) when the velocity is constant

(this makes sense if you are always traveling 4 m/s then your average velocity will also be 4m/s)

Question 55

22) Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

Answer 55

A) The acceleration is toward the east.

(there is no such thing as deceleration only acceleration in the opposite direction “east” of the direction traveled “west”)

Question 56

23) An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object

Answer 56

D) is increasing its velocity by 2.0 m/s every second.

(acceleration is change in velocity/time, +2.0 m/s² acceleration would be an increase in velocity of 2 m/s per s = 2m/s²)

Question 57

24) Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?

Answer 57

D) The acceleration is equal to zero.

(at constant velocity there is no acceleration because there is no change in velocity/time)

(future priming if a=0, then there is no force,F = m(a), F =m(0) therefore F=0)

Question 58

25) When a ball is thrown straight up with no air resistance, the acceleration at its highest point

Answer 58

B) is downward

(acceleration is g=9.8m/s²)

g is the force of gravity pulling the ball back down to earth, always points down

which is why the higher the ball goes the slower (decrease in velocity) it goes until it finally stops (v=0) and begins to return to the earth with the same acceleration (g) now going with the balls movement and not against it.

if g were 0 the ball would just stay stuck in the air and never come down

this would be shitty

Question 60

26) Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point?

Answer 60

C) exactly g

(acceleration is g=9.8m/s²)

g is the force of gravity pulling the ball back down to earth, always points down

which is why the higher the ball goes the slower (decrease in velocity) it goes until it finally stops (v=0) and begins to return to the earth with the same acceleration (g) now going with the balls movement and not against it.

if g were 0 the ball would just stay stuck in the air and never come down

this would be shitty

Question 61

27) An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is

Answer 61

C) a straight line making an angle with the time axis.

(position increases with time at a constant rate)

Question 62

28) An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is

Answer 62

A) a horizontal straight line.

(no change in velocity, therefore acceleration = 0)

(no change in y value “velocity” as x value “time” increases)

Question 63

(

Question 64

29) The slope of a position versus time graph gives

Answer 64

B) velocity.

change in position = displacement

velocity = change in displacement/change in time

Question 65

31) If the position versus time graph of an object is a horizontal line, the object is

Answer 65

C) at rest.

(object is not moving so no change in position, ‘y’ value is constant as time “x” value increases

Question 66

32) If the velocity versus time graph of an object is a horizontal line, the object is

Answer 66

A) moving with zero acceleration.

(no change in velocity, therefore acceleration = 0)

(no change in y value “velocity” as x value “time” increases) =

Question 67

33) If the velocity versus time graph of an object is a straight line making an angle of +30°

Answer 67

B) moving with constant non-zero acceleration.

value for velocity ‘y’ increase as time ‘x’ increases

acceleration = change in velocity/ time

Question 68

34) Which of the following graphs represent an object at rest? (There could be more than one correct choice.)

Answer 68

Answer: A (no change in position ‘y’ as time ‘x’ increases = horizontal line

B is moving at a non constant velocity increasing over time

C is moving at a constant velocity towards the observer

D is a rapid change in position (like teleportation)

E is a constant velocity (no acceleration)

Question 69

35) Which of the following graphs represent an object having zero acceleration?

A) only graph a

B) only graph b

C) graphs a and b

D) graphs b and c

E) graphs c and d

Answer 69

Answer: C

(a is a constant change in position over time, constant velocity = 0 acceleration)

(b is also a constant velocity = 0 accelration)

C,D both involve changes in velocity with time meaning there is some value of acceleration occurring

Question 70

36) If, in the figure, you start from the Bakery, travel to the Cafe, and then to the Art Gallery
(a) what distance you have traveled?
(b) what is your displacement?

Answer 70

(a) 10.5 km

scalar - distance is total movement made (4km + 4km+ 2.5km) = 10.5 km

(b) 2.50 km south

vector (magnitude and direction)- displacement is total productive movement requires both distance and direction

(+4km + -4km + -2.5km) = -2.5 km or 2.5 km south

Question 71

37) An object moves 15.0 m north and then 11.0 m south. Find both the distance it has traveled and the magnitude of its displacement.

Answer 71

B) 26.0 m, 4.0 m North

distance is scalar (15m + 11m) = 26m

displacement is vector and requires direction and magnitude (+15m + - 11m) = + 4m or 4m North

Question 72

38) What must be your average speed in order to travel 350 km in 5.15 h?

Answer 72

C) 68.0 km/h

speed = distance over time

Question 73

39) A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. What was the average speed of the runner in m/s?

Answer 73

C) 3.95 m/s

42km = 42000m

2 hours = 120min+57min = 177min (60sec/1min) = 1060sec

42000m/1060sec = 3.95m/s

Question 74

40) If you are driving 72 km/h along a straight road and you look to the side for 4.0 s, how far do you travel during this inattentive period?

Answer 74

D) 80 m

72km/h(1h/3600sec) = .02km or 20m/s (4s) = 80m

Question 75

You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it:

A) moves along a straight-line path away from the center of the circle.

B) moves along a straight-line path toward the center of the circle.

C) moves along a straight-line path in its original direction.

D) continues to follow a circular path, but with a radius larger than the original radius.

E) moves along a path that is neither straight nor circular.

Answer 75

C) moves along a straight-line path in its original direction.

Question 76

When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path?

A) the normal force from the road

B) the friction force from the road

C) gravity

D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

Answer 76

B) the friction force from the road

Question 77

A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road?

A) tangent to the curve in the forward direction

B) tangent to the curve opposite to the direction of the car’s motion

C) perpendicular to the curve outward

D) perpendicular to the curve inward

E) There is no friction on the car because its speed is constant.

Answer 77

D) perpendicular to the curve inward

Question 78

When an object moves in uniform circular motion, the direction of its acceleration is

A) in the same direction as its velocity vector.

B) in the opposite direction of its velocity vector.

C) is directed toward the center of its circular path.

D) is directed away from the center of its circular path.

E) depends on the speed of the object.

Answer 78

C) is directed toward the center of its circular path.

Question 79

When a car goes around a banked circular curve at the proper speed for the banking angle, what force cause it to follow the circular path?

A) the normal force from the road

B) the friction force from the road

C) gravity

D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

Answer 79

A) the normal force from the road

Question 80

A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth’s gravity?

A) when it gets above the atmosphere

B) when it is half-way there

C) when it is closer to the Moon than it is to Earth

D) It is never beyond the pull of Earth’s gravity.

Answer 80

D) It is never beyond the pull of Earth’s gravity.

Question 81

If you stood on a planet having a mass four times that of Earth’s mass, and a radius two times that of Earth’s radius, you would weigh

A) the same as you do on Earth.

B) two times more than you do on Earth.

C) two times less than you do on Earth.

D) four times more than you do on Earth.

Answer 81

A) the same as you do on Earth.

Question 82

Two cars go around a banked curve at the proper speed for the banking angle. One car has tires with excellent traction, while the other car has bald slippery tires. Which of these cars is more likely to slide on the pavement as it goes around the curve?

A) the car with the new tires

B) the car with the bald tires

C) Neither car will slide.

D) It depends on if the pavement is wet or dry.

Answer 82

C) Neither car will slide.

Question 83

A piece of space debris is released from rest at an altitude that is two earth radii from the center of the earth. Compared to its weight on Earth, the weight of this debris is

A) zero.

B) the same as on the surface of the earth.

C) one-half of its weight on the surface of the earth.

D) one-third of its weight on the surface of the earth.

E) one-quarter of its weight on the surface of the earth.

Answer 83

E) one-quarter of its weight on the surface of the earth.

Question 84

The reason an astronaut in an earth satellite feels weightless is that

A) the astronaut is beyond the range of the earth’s gravity.

B) the astronaut is falling.

C) the astronaut is at a point in space where the effects of the moon’s gravity and the earth’s gravity cancel.

D) this is a psychological effect associated with rapid motion.

E) the astronaut’s acceleration is zero.

Answer 84

B) the astronaut is falling.

Question 85

Halley’s Comet is in a highly elliptical orbit around the sun. Therefore, the orbital speed of Halley’s Comet, while traveling around the sun,

A) is constant.

B) increases as it nears the Sun.

C) decreases as it nears the Sun.

D) is zero at two points in the orbit.

Answer 85

B) increases as it nears the Sun.

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Question 139

130) A 40-kg crate is being lowered with a downward acceleration is 2.0 m/s2 by means of a rope.

1. What is the magnitude of the force exerted by the rope on the crate?
2. What would be the magnitude of the force exerted by the rope if the crate were being raised with an acceleration of 2.0 m/s2?

Answer 139

Question 140

131) A certain aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed is 27.0 m/s. If the braking force is a constant 445,000 N, what is the speed of the airplane 10.0 s later?

A) 10.0 m/s

B) 12.2 m/s

C) 14.0 m/s

D) 18.0 m/s

Answer 140

Question 141

132) What magnitude net force is required to accelerate a 1200-kg car uniformly from 0 m/s to 27.0 m/s in 10.0 s?

A) 444 N

B) 1620 N

C) 3240 N

D) 4360 N

E) 11800 N

Answer 141

Question 142

133) A 1200-kg car is pulling a 500-kg trailer along level ground. Friction of the road on the trailer is negligible. The car accelerates with an acceleration of 1.3 m/s2. What is the force exerted by the car on the trailer?

A) 550 N

B) 600 N

C) 650 N

D) 700 N

E) 750 N

Answer 142

Question 143

134) During a hard stop, a car and its passengers slow down with an acceleration of 8.0 m/s2. What magnitude force does a 50-kg passenger exert on the seat belt in such a stop?

Answer 143

Question 144

135) A box of mass 72 kg is at rest on a horizontal frictionless surface. A constant horizontal force of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box 3.4 seconds to travel 13 meters. What is the magnitude of the force F?

Answer 144

Question 145

136) A 958-N rocket is coming in for a vertical landing. It starts with a downward speed of 25 m/s and must reduce its speed to 0 m/s in 8.0 s for the final landing.
(a) During this landing maneuver, what must be the thrust due to the rocket’s engines?
(b) What must be the direction of the engine thrust force?

Answer 145

Question 146

137) A 10-kg object is hanging by a very light wire in an elevator that is traveling upward. The tension in the rope is measured to be 75 N. What are the magnitude and direction of the acceleration of the elevator?

Answer 146

Question 147

138) A 50.0-kg crate is being pulled along a horizontal smooth surface. The pulling force is 10.0 N and is directed 20.0° above the horizontal. What is the magnitude of the acceleration of the crate?

A) 0.0684 m/s2

B) 0.188 m/s2

C) 0.200 m/s2

D) 0.376 m/s2

E) 0.0728 m/s2

Answer 147

Question 148

139) A 40-kg box is being pushed along a horizontal smooth surface. The pushing force is 15 N 29 directed at an angle of 15° below the horizontal. What is the magnitude of the acceleration of the crate?

A) 0.16 m/s2

B) 0.36 m/s2

C) 0.47 m/s2

D) 0.39 m/s2

E) 0.68 m/s2

Answer 148