Midterm 1 Flashcards
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 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
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
v^2=u^2+2(a)(s)
42^2=0 + 2a x 5600
a=0.1575=0.16
Answer A)
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.
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
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
C) 45 m/s
2 x 15= 30 m/s
30+15= 45m/s
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: 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
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?
44) A water rocket can reach a speed of 75 m/s in 0.050 seconds from launch. What is its average acceleration?
70/.050= 1500
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?
total velocity= 3m/s + 2m/s= 5m/s
time= displacement/velocity
100/5= 20seconds
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?
R = 5m , T = 8sec weight =670N
V = ω × R
V = (2π/(8))×R
V = 3.928m/s
M = 670/(9.8) = 68.367kg
Wapp = W + Mv2/R
Wapp = 670 + ((68.367)(3.928)2/(5))
Wapp = 880N (approx.)
4) Convert 1.2 × 10-3 to decimal notation.
D.
10-3 means move decimal left 3 places = 0.0012
8) The number 0.003010 has
C) 4 significant figures.
0.003010leading zeros do not count
7) 0.00325 × 10-8 cm can also be expressed in mm as
C) 3.25 × 10-10 mm. (1cm = 10mm) 0.00325 × 10-8 = 0.325 × 10-11
6) 0.0001776 can also be expressed as
B. 1.776 × 10-4.
3) The current definition of the standard kilogram of mass is based on
C.
the mass a particular object kept in France (Le Grand K)
2) The current definition of the standard second of time is based on
A.
the frequency of radiation emitted by cesium atoms (cesium-133 clock)
1)The current definition of the standard meter of length is based on
C.
distance traveled by light in a vacuum = 1/299,792,458 of a second.
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.
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
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?
Speed = distance/time
4+4+2.5/2= 5.25 km/h
average velocity= displacement/time
2.5/2=1.25 km/h
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?
117 milliseconds
20 x 2= 40 meters
40/340= 0.117 seconds= 117 milliseconds
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
D) 80 m
72 km/hr x 1000/3600= 20 m/s
20 x 4= 80meters
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.
D) in a general northwesterly direction.
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
C) the push of box G against you.
Newton’s Third Law
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.
A) is always zero.
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.
B) remains a non-zero constant.
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.
B) parallel to each other (in the same direction).
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.
B) could be as small as 2.0 m or as large as 12 m.
7-5=2
7+5=12
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
Vf= Vi + at
t= 10/2= 5
0= Vi + (-9.8)(5)
Vi= 49 m/s
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
The speed of the hammer is
V= Vi - at= 14-28= -14 m/s
acceleration absolute value= 14m/s
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?
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
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
v = u+at
v = 7-9.8*0.5
v = 2.1 m/s
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?
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
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?
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
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
E) 160
5) Write out the number 7.35 × 10-5 in full with a decimal point and correct number of zeros.
B.
10-5 mean move decimal 5 places left = 0.0000735
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.
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
8) The number 0.003010 has
C) 4 significant figures.
9) What is to the proper number of significant figures in 0.674/0.74
A.
- 91
(0. 74 only has 2 sig figs and determines sig figs for the answer)
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: 42 m/s at 31° north of west
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°
A) 75°
Angle = cos^-1 (1.8/7) = 75
Kepler’s Third Law for a Circular Orbit Equation
The speed of a satellite is the distance traveled during one period and is calculated by the following:
10) What is the sum of 1.53 + 2.786 + 3.3 written with the correct number of significant figures?
B. 7.6
(3.3 only has 2 sig figs and determines sig figs for the answer)
11) What is the product of 11.24 and 1.95 written with the correct number of significant figures?
B.
21.9 (1.95 has 3 sig figs and determines sig figs for the answer)
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
A) 4.8 m/s
Use Pythagorean Theorem to calculate Y component of vector
12) Express (4.3 × 106)-1/2 in scientific notation.
A.
4.8 × 10-4 (-½ power is = 1/x-2)
(-2 power = square root)
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
C.
0.682 m2 (least sig figs is 0.606 with 3 sig figs)
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
C) 0.118 m2 ( 1.27 ft2 ) (144in2/1ft2) (6.45cm2/1in2) (1m2/10000cm2)
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)
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
16) A weight lifter can bench press 171 kg How many milligrams (mg) is this?
A) 1.71 × 108 mg (171kg) (1000g/kg)(1000mg/1g) or (1.71x102)(1x106)
17) How many nanoseconds does it take for a computer to perform one calculation if it performs 6.7x107 calculations per second?
A) 15 ns 1 sec/6.7x107calc = 1.5x10-8 sec/1calc.
(1 sec = 1x10-9 nano sec)
18) The shortest wavelength of visible light is approximately 400 nm. Express this wavelength in centimeters.
A) 4 × 10-5 cm (400nm = 400x10-9m or 4x10-7m)
4x10-7m (100 cm/1m)
19) Convert a speed of 4.50 km/h to units of ft/min. (1.00 m = 3.28 ft)
D) 246 ft/min 4.5km/hr = (4500m/hr)(3.28 ft/1m) = 14760ft/hr(1hr/60min)
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
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
21) When is the average velocity of an object equal to the instantaneous velocity?
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)
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?
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”)
23) An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object
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)
24) Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct?
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)
25) When a ball is thrown straight up with no air resistance, the acceleration at its highest point
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
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?
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
27) An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is
C) a straight line making an angle with the time axis.
(position increases with time at a constant rate)
28) An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is
A) a horizontal straight line.
(no change in velocity, therefore acceleration = 0)
(no change in y value “velocity” as x value “time” increases)
(
29) The slope of a position versus time graph gives
B) velocity.
change in position = displacement
velocity = change in displacement/change in time
31) If the position versus time graph of an object is a horizontal line, the object is
C) at rest.
(object is not moving so no change in position, ‘y’ value is constant as time “x” value increases
32) If the velocity versus time graph of an object is a horizontal line, the object is
A) moving with zero acceleration.
(no change in velocity, therefore acceleration = 0)
(no change in y value “velocity” as x value “time” increases) =
33) If the velocity versus time graph of an object is a straight line making an angle of +30°
B) moving with constant non-zero acceleration.
value for velocity ‘y’ increase as time ‘x’ increases
acceleration = change in velocity/ time
34) Which of the following graphs represent an object at rest? (There could be more than one correct choice.)
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)
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: 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
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?
(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
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.
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
38) What must be your average speed in order to travel 350 km in 5.15 h?
C) 68.0 km/h
speed = distance over time
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?
C) 3.95 m/s
42km = 42000m
2 hours = 120min+57min = 177min (60sec/1min) = 1060sec
42000m/1060sec = 3.95m/s
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?
D) 80 m
72km/h(1h/3600sec) = .02km or 20m/s (4s) = 80m
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.
C) moves along a straight-line path in its original direction.
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.
B) the friction force from the road
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.
D) perpendicular to the curve inward
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.
C) is directed toward the center of its circular path.
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.
A) the normal force from the road
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.
D) It is never beyond the pull of Earth’s gravity.
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.
A) the same as you do on Earth.
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.
C) Neither car will slide.
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.
E) one-quarter of its weight on the surface of the earth.
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.
B) the astronaut is falling.
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.
B) increases as it nears the Sun.
130) A 40-kg crate is being lowered with a downward acceleration is 2.0 m/s2 by means of a rope.
- What is the magnitude of the force exerted by the rope on the crate?
- 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?
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
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
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
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?
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?
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?
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?
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
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
