Physics

Question 1

Set 1 Problem 3: A bicycle tire has a diameter of 24 inches. From rest it accelerates at a constant rate of 2ft/sec². What is the angular velocity when it has traveled 1 mile?

Answer 1

145.33 rad/sec (p.7)

Question 2

Set 1 Problem 73: A point on the rim of the wheel has a linear speed of 12 cm/sec. If the radius of the wheel is 20 cm, what is the angular speed of the wheel in rad/sec?

Answer 2

0.60 rad/sec

Question 3

Set 2 Problem 2: In a car race, the rate of one car is 120 km/hr and the rate of another is 105 km/hr. If the faster car finished the race 20 minutes before the slower one, what was the distance of the race?

Answer 3

280 km (p. 22)

Question 4

Set 3 Problem 33: MCIA is designing an airport for small planes. This is use for airplanes that must reach a speed before takeoff of at least 100 kph and can accelerate at 2 m/s². Find the minimum length must the runway have.

Answer 4

192.90 m (p. 47)

Question 5

Set 3 Problem 63: An elastic cord vibrates with a frequency of 3.0 Hz when a mass of 0.50 kg is hung from it. What will its frequency be if only 0.24 kg hangs from it?

Answer 5

4.33 Hz (p.53)

Question 6

Set 4 Problem 6: A ball is thrown vertically upward with an initial velocity of 4 m/s from the window of a tall building. The ball strikes the sidewalk at the ground level 5 seconds later. How high is the window above the ground level?

Answer 6

102.625 m (p.60)

Question 7

Set 4 Problem 22: From a speed of 20 mph, a train accelerates 0.395 m/s². How long in seconds will it takes the train to travel one kilometer during the acceleration?

Answer 7

52.10 sec (p.62)

Question 8

Set 4 Problem 43: A projectile is thrown from the top of a building 30 m high above the ground with a velocity of 300 m/s directed at an angle of 20° from the horizontal. How long will the ball hit the ground?

Answer 8

21.2 sec (p.66)

Question 9

Set 5 Problem 41: A flywheel rotating at 3 rev per sec has its speed increased at a constant rate of 40 rad per min each second during an interval of 15 sec. How many revolutions does does it make this time interval?

Answer 9

57 rev (p.84)

Question 10

Set 6 Problem 17: Determine the velocity of escape of Mars if the acceleration of gravity at the surface of Mars is 0.38g where g=9.81m/s² and the radius of Mars is 2,100 miles.

Answer 10

3.10 mi/s (p.96)

Question 11

Set 7 Problem 20: A motor boat takes 1 1/2 times as long to go 160 miles upstream as it goes to return. If the boat cruises at 40 mph in still water, what is the speed of the current?

Answer 11

8 mph (p.114)

Question 12

Set 7 Problem 39: A 200-lb chain is 100 ft long and hangs vertically from the top of a tall building. How much work is required to lift the chain to the top of the building?

Answer 12

10,000 ft-lb (p.117)

Question 13

Set 7 Problem 40: Find the center of mass from the x-axis of a semicircle bounded by x²+y²=16 and the x-axis.

Answer 13

1.70 (p.117)

Question 14

Set 7 Problem 44: A flywheel is revolving at a speed of 60 revolutions per minute and is to be brought to a complete stop in 12 seconds. How many revolutions the flywheel will still make before it stops if it undergoes a uniform deceleration within the time interval?

Answer 14

6 rev (p.117)

Question 15

Set 7 Problem 45: A flywheel is uniformly accelerated from rest at an angular acceleration 10 rev/s^2 for 15 seconds. Compute the final angular velocity.

Answer 15

150 rev/s (p.118)

Question 16

Set 7 Problem 59: A marksman fires a bullet to a target. Three seconds later, he heard the bullet hits the target. If the speed of the bullet is 800 m/s and the speed of sound is 300 m/s, how far is the target?

Answer 16

654.55 m (p.120)

Question 17

Set 8 Problem 8: An airplane flying with the wind took 2 hours to travel 1,000 km and 2.5 hours to fly back. What was the wind velocity in kph?

Answer 17

50 kph (p.129)

Question 18

Set 8 Problem 13: A 50 kg block is resisting on an inclined plane making an angle of 24deg with the horizontal. If the coefficient of friction between the plane and the block is 0.60, determine the force parallel to the inclined plane that must be applied to cause an impending motion up the plane.

Answer 18

468.4 N (p.130)

Question 19

Set 8 Problem 49: Compute the velocity of escape from the moon if the radius of the moon is 1,080 mi and the gravitational acceleration at the surface of the moon is 0.165 times the gravitational acceleration at the earth’s surface.

Answer 19

1.47 mi/s (p.136)

Question 20

Set 8 Problem 50: According to Hooke’s Law, the force required to stretch a helical spring is proportional to the distance stretched. The natural length of a given spring is 10 cm. A force of 4 kg will stretch it to a total length of 12 cm. Find the work done in stretching it from its natural length to a total length of 16 cm.

Answer 20

3.53 J (p.136)

Question 21

Set 9 Problem 17: A stone is dropped from the top of a building 50 m high. After it has fallen 10 m below, a second stone is thrown vertically upward from the ground. What must be the initial velocity of the second stone so that both reach the ground at the same time?

Answer 21

8.63 m/s (p.147)

Question 22

Set 9 Problem 22: Objects A and B with the same masses, 5 kg undergo a a direct central impact. Before the impact, A is moving to the right with a velocity of 6 m/s and B is stationary. Determine the velocity of B after impact if the impact is perfectly elastic.

Answer 22

6 m/s (p.149)

Question 23

Set 9 Problem 24: The electrical resistance of a wire varies inversely as the square of its radius. Given that the resistance is 0.8 ohms when the radius is 20 mm, find the resistance when the radius is 30 mm.

Answer 23

0.36 ohm (p.149)

Question 24

Set 9 Problem 39: A 10-kg block is supported by a cord and pulled upward with an acceleration 3 m/s^2. What is the tension in the cord?

Answer 24

128 N (p.151)

Question 25

Set 9 Problem 40: A set out to walk at the rate of 4 km an hour. After he had been walking 2 3/4 hours, B set out to overtake him and went 4 1/2 km the first hour, 4 3/4 the second hour, 5 km the third hour and so on gaining a quarter of a km every hour. In how many hours would B overtake A?

Answer 25

8 hours (p.151)

Question 26

Set 9 Problem 70: What retarding force is required to stop a 0.45 caliber bullet of mass 20 grams and speed of 350 m/sec, as it penetrates a wooden block to a depth of 75 cm?

Answer 26

16,333.33 (p.156)

Question 27

A 100 kg block is moving horizontally to the right on a plane surface at a constant velocity of 3 m/s. The coefficient of friction between the block and the surface is 0.30. At a certain instant, a horizontal force of 400 N pushes the body to the right.
Set 10 Problem 39: What is the acceleration of the body after the force is applied?

Answer 27

1.057 m/s^2 (p.169)

Question 28

A 100 kg block is moving horizontally to the right on a plane surface at a constant velocity of 3 m/s. The coefficient of friction between the block and the surface is 0.30. At a certain instant, a horizontal force of 400 N pushes the body to the right.
Set 10 Problem 40: What is the velocity of the block 5 seconds after the force is applied?

Answer 28

8.285 m/s (p.169)

Question 29

A 100 kg block is moving horizontally to the right on a plane surface at a constant velocity of 3 m/s. The coefficient of friction between the block and the surface is 0.30. At a certain instant, a horizontal force of 400 N pushes the body to the right.
Set 10 Problem 41: How many seconds after the force is applied will the block travel a distance of 50 m?

Answer 29

7.29 s (p.169)

Question 30

Set 10 Problem 43: A projectile is shot at an angle of 60° above the horizontal and strikes a vertical wall 24.40 m away from a point 14.6 m above the point of projection. Find the initial velocity.

Answer 30

20.55 m/s (p.169)

Question 31

Set 10 Problem 48: At what rpm must a disk be rotated about its vertical axis so that the radial acceleration of a point 1 cm from the axis is 2000g where g=9.81 m/s^2?

Answer 31

13,376 rpm (p.170)