physics 1401 chapter 6 review-new - austin community ... exam 2.pdf · review exam 2.doc - 1 -...

Review Exam 2.doc - 1 -

Physics 1401

Chapter 6 Review-New

CHAPTER 6

2.

A rock is dropped from a high tower and falls freely under the influence of gravity.

Which one of the following statements is true concerning the rock as it falls?

(a) It will gain an equal amount of momentum during each second.

(b) It will gain an equal amount of kinetic energy during each second.

(c) It will gain an equal amount of speed for each meter through which it falls.

(d) It will gain an equal amount of momentum for each meter through which it falls.

(e) The amount of momentum it gains will be proportional to the amount of potential

energy that it loses.

3. 3. A stunt person jumps from the roof of a tall building, but no injury occurs because the

person lands on a large, air-filled bag. Which one of the following best describes why

no injury occurs?

(a) The bag provides the necessary force to stop the person.

(b) The bag reduces the impulse to the person.

(c) The bag increases the amount of time the force acts on the person and reduces the

change in momentum.

(d) The bag decreases the amount of time during which the momentum is changing and

reduces the average force on the person.

(e) The bag increases the amount of time during which the momentum is changing

and reduces the average force on the person.

5. A 1.0-kg ball has a velocity of 12 m/s downward just before it strikes the ground and

bounces up with a velocity of 12 m/s upward. What is the change in momentum of the

ball?

(a) zero kg • m/s (c) 12 kg • m/s, upward (e) 24 kg • m/s, upward

(b) 12 kg • m/s, downward (d) 24 kg • m/s, downward


9.

A 0.065-kg tennis ball moving to the right with a speed of 15 m/s is struck by a tennis

racket, causing it to move to the left with a speed of 15 m/s. If the ball remains in

contact with the racquet for 0.020 s, what is the magnitude of the average force

experienced by the ball?

(a) zero newtons (c) 160 N (e) 9.8 ⋅ 104 N

(b) 98 N (d) 1.6 ⋅ 105 N

12. While a car is stopped at a traffic light in a storm, raindrops strike the roof of the car.

The area of he roof is 5.0 m2. Each raindrop has a mass of 3.7 ⋅ 10

–4 kg and speed of 2.5

m/s before impact and is at rest after the impact. If, on average at a given time, 150

raindrops strike each square meter, what is the impulse of the rain striking the car?

(a) 0.69 N • s (c) 0.14 N • s (e) 21 N • s

(b) 0.046 N • s (d) 11 N • s

15. A football player kicks a 0.41-kg football initially at rest; and the ball flies through the

air. If the kicker’s foot was in contact with the ball for 0.051 s and the ball’s initial

speed after the collision is 21 m/s, what was the magnitude of the average force on the

football?

(a) 9.7 N (c) 81 N (e) 210 N

(b) 46 N (d) 170 N


Questions 16 and 17 pertain to the situation described below: A 4.0-kg block slides along a frictionless surface with a constant speed of 5.0 m/s. Two

seconds after it begins sliding, a horizontal, time-dependent force is applied to the mass.

The force is removed eight seconds later. The graph shows how the force on the block

varies with time.

16.

What is the magnitude of the total impulse of the force acting on the block?

(a) 20 N • s (c) 48 N • s (e) 60 N • s

(b) 42 N • s (d) 54 N • s

17. What, approximately, is the speed of the block at t = 11 seconds?

(a) 5.0 m/s (c) 25 m/s (e) 75 m/s

(b) 16 m/s (d) 65 m/s

21. A 50-kg toboggan is coasting on level snow. As it passes beneath a bridge, a 20-kg

parcel is dropped straight down and lands in the toboggan. If (KE)1 is the original

kinetic energy of the toboggan and (KE)2 is the kinetic energy after the parcel has been

added, what is the ratio (KE)2/(KE)1.

(a) 0.4 (c) 0.7 (e) 1

(b) 0.6 (d) 0.8


Ans. c.

25.

An 80-kg astronaut carrying a 20-kg tool kit is initially drifting toward a stationary

space shuttle at a speed of 2 m/s. If she throws the tool kit toward the shuttle with a

speed of 6 m/s as seen from the shuttle, her final speed is

(a) 1 m/s toward the shuttle. (d) 4 m/s toward the shuttle.

(b) 1 m/s away from the shuttle. (e) 6 m/s away from the shuttle.

(c) 2 m/s toward the shuttle.

28. Two objects of equal mass traveling toward each other with equal speeds undergo a

head on collision. Which one of the following statements concerning their velocities

after the collision is necessarily true?

(a) They will exchange velocities. (d) Their velocities will be zero.

(b) Their velocities will be reduced. (e) Their velocities may be zero.

(c) Their velocities will be unchanged.


31. Complete the following statement: Momentum will be conserved in a two-body

collision only if

(a) both bodies come to rest.

(b) the collision is perfectly elastic.

(c) the kinetic energy of the system is conserved.

(d) the net external force acting on the two-body system is zero.

(e) the internal forces of the two body system cancel in action-reaction pairs.

39.

A 50.0-kg boy runs at a speed of 10.0 m/s and jumps onto a cart as shown in the figure.

The cart is

initially at rest.

If the speed of the cart with the boy on it is 2.50 m/s, what is the mass of the cart?

(a) 150 kg (c) 210 kg (e) 300 kg

(b) 175 kg (d) 260 kg


42. A 35-kg girl is standing near and to the left of a 43-kg boy on the frictionless surface of

a frozen pond. The boy tosses a 0.75-kg ice ball to the girl with a horizontal speed of 6.2

m/s. What are the velocities of the boy and the girl immediately after the girl catches the

ice ball?

girl boy

(a) 0.81 m/s, left 0.67 m/s, right

(b) 0.17 m/s, left 0.14 m/s, left

(c) 0.18 m/s, right 0.13 m/s, left

(d) 0.42 m/s, left 0.49 m/s, right

(e) 0.13 m/s, left 0.11 m/s, right

50. In the game of billiards, all the balls have

approximately the same mass, about 0.17 kg.

In the figure, the cue ball strikes another ball

such that it follows the path shown. The other

ball has a speed of 1.5 m/s immediately after

the collision. What is the speed of the cue

ball after the collision?

(a) 1.5 m/s (c) 2.6 m/s (e) 5.2 m/s

(b) 1.8 m/s (d) 4.3 m/s

64. A 100-kg fisherman and a 500-kg supply crate are on a frozen pond that is essentially

frictionless. The man and the crate are initially separated by a distance of 600 meters.

The fisherman uses a very light rope to pull the crate closer to him. How far has the man

moved when the crate reaches the fisherman?

(a) zero meters (c) 50 m (e) 500 m

(b) 10 m (d) 100 m


Physics 1401

Chapter 7-New

2. The second hand on a watch has a length of 4.50 mm and makes one revolution in

60.00 s. What is the speed of the end of the second hand as it moves in uniform circular

motion?

(a) 9.42 × 10-4 m/s (c) 5.34 × 10-

3 m/s (e) 2.36 × 10-

5 m/s

(b) 2.67 × 10-3 m/s (d) 4.71 × 10-

4 m/s

3. Approximately one billion years ago, the Moon orbited the Earth much closer than it

does today. The radius of the orbit was only 24 400 km. Today, the radius is 385 000 km.

The orbital period was only 23 400 s. The present period is 2.36 × 106 s. Assume that the

orbit of the Moon is circular. Calculate the ratio of the speed of the Moon in its ancient

orbit to the speed that it has today.

(a) 15.8 (c) 10.2 (e) 6.39

(b) 12.8 (d) 7.15

5. A ball is whirled on the end of a string in a horizontal circle of radius R at constant

speed v. The centripetal acceleration of the ball can be increased by a factor of 4 by

(a) keeping the speed fixed and increasing the radius by a factor of 4.

(b) keeping the radius fixed and increasing the speed by a factor of 4.

(c) keeping the radius fixed and increasing the period by a factor of 4.

(d) keeping the radius fixed and decreasing the period by a factor of 4.

(e) keeping the speed fixed and decreasing the radius by a factor of 4.

7. A car traveling at 20 m/s rounds a curve so that its centripetal acceleration is 5 m/s2.

What is the radius of the curve?

(a) 4 m (c) 80 m (e) 640 m

(b) 8 m (d) 160 m


8. A satellite is placed in a circular orbit to observe the surface of Mars from an altitude

of 144 km. The equatorial radius of Mars is 3397 km. If the speed of the satellite is 3480

m/s, what is the magnitude of the centripetal acceleration of the satellite?

(a) 2.17 m/s2 (c) 2.99 m/s

2 (e) 4.05 m/s

2

(b) 2.60 m/s2 (d) 3.42 m/s

2

11. A boy is whirling a stone around his head by means of a string. The string makes one

complete revolution every second, and the tension in the string is FT. The boy then

speeds up the stone, keeping the radius of the circle unchanged, so that the string makes

two complete revolutions every second. What happens to the tension in the sting?

(a) The tension is unchanged.

(b) The tension reduces to half of its original value.

(c) The tension increases to twice its original value.

(d) The tension increases to four times its original value.

(e) The tension reduces to one-fourth of its original value.

14. Sara puts a box into the trunk of her car. Later, she drives around an unbanked curve

that has a radius of 48 m. The speed of the car on the curve is 16 m/s, but the box remains

stationary relative to the floor of the trunk. Determine the minimum coefficient of static

friction for the box on the floor of the trunk.

(a) 0.42 (d) 0.33

(b) 0.54 (e) This cannot be determined without knowing the mass of

(c) 0.17 the box.

15. In an amusement park ride, a small child stands against the wall of a cylindrical room

that is then made to rotate. The floor drops downward and the child remains pinned

against the wall. If the radius of the device is 2.15 m and the relevant coefficient of

friction between the child and the wall is 0.400, with what minimum speed is the child

moving if he is to remain pinned against the wall?

(a) 7.26 m/s (c) 12.1 m/s (e) 9.80 m/s

(b) 3.93 m/s (d) 5.18 m/s


18. The maximum speed at which a car can safely negotiate an unbanked curve depends

on all of the following factors except

(a) the diameter of the curve.

(b) the acceleration due to gravity.

(c) the coefficient of static friction between the road and the tires.

(d) the coefficient of kinetic friction between the road and the tires.

(e) the ratio of the static frictional force between the road and the tires and the

normal force exerted on the car.

20. Determine the minimum angle at which a roadbed should be banked so that a car

traveling at 20.0 m/s can safely negotiate the curve if the radius of the curve is

2.00 × 102 m.

(a) 0.200° (c) 11.5° (e) 78.2°

(b) 0.581° (d) 19.6°

Questions 23 through 25 pertain to the statement below: A 1000-kg car travels along a straight 500-m portion of highway (from A to B) at a

constant speed of 10 m/s. At B, the car encounters an unbanked curve of radius 50 m. The

car follows the road from B to C traveling at a constant speed of 10 m/s while the

direction of the car changes from east to south.

23. What is the magnitude of the acceleration of the car as it travels from A to B?

(a) 2 m/s2 (c) 10 m/s

2 (e) zero m/s

2

(b) 5 m/s2 (d) 20 m/s

2

24. What is the magnitude of the acceleration of the car as it travels from B to C?

(a) 2 m/s2 (c) 10 m/s

2 (e) zero m/s

2

(b) 5 m/s2 (d) 20 m/s

2

25. What is the magnitude of the frictional force between the tires and the road as the car

negotiates the curve from B to C?

(a) 20 000 N (c) 5000 N (e) 1000 N

(b) 10 000 N (d) 2000 N


26. The earth exerts the necessary centripetal force on an orbiting satellite to keep it

moving in a circle at constant speed. Which statement best explains why the speed of the

satellite does not change although there is a net force exerted on it?

(a) The satellite is in equilibrium.

(b) The acceleration of the satellite is zero m/s2.

(c) The centripetal force has magnitude mv2/r.

(d) The centripetal force is canceled by the reaction force.

(e) The centripetal force is always perpendicular to the velocity.

30. A satellite is placed in equatorial orbit above Mars, which has a radius of 3397 km

and a mass MM = 6.40 × 1023 kg. The mission of the satellite is to observe the Martian

climate from an altitude of 488 km. What is the orbital period of the satellite?

(a) 9.18 × 102

s (c) 7.36 × 103 s (e) 7.27 × 10

12 s

(b) 3.62 × 103 s d) 1.08 × 10

5 s

45. A 25-kg box is sliding down an ice-covered hill. When it

reaches point A, the box is moving at 11 m/s. Point A is at the

bottom of a circular arc that has a radius R = 7.5 m. What is the

magnitude of the normal force on the box at Point A?

(a) 250 N (d) 650 N

(b) 280 N (e) 900 N

(c) 400 N


Questions 49 through 52 pertain to the situation described below: A 1500-kg car travels at a constant speed of 22 m/s around a circular track that has a

radius of 85 m.

49. Which statement is true concerning this car?

(a) The velocity of the car is changing.

(b) The car is characterized by constant velocity.

(c) The car is characterized by constant acceleration.

(d) The car has a velocity vector that points along the radius of the circle.

(e) The car has an acceleration vector that is tangent to the circle at all times.

50. What is the magnitude of the acceleration of the car?

(a) 5.7 m/s2 (c) 9.8 m/s

2 (e) zero m/s

2

(b) 0.26 m/s2 (d) 1.2 m/s

2

51. What is the average velocity of the car during one revolution?

(a) 8.0 m/s (c) 26 m/s (e) zero m/s

(b) 12 m/s (d) 44 m/s

52. Determine the magnitude of the net force that acts on the car.

(a) 390 N (c) 8.5 × 103 N (e) zero newtons

(b) 1800 N (d) 1.5 × 104 N

53. Jupiter has a mass that is roughly 320 times that of the Earth and a radius equal to 11

times that of the Earth. What is the acceleration due to gravity on the surface of Jupiter?

(a) 2.7 m/s2 (c) 26 m/s

2 (e) 260 m/s

2

(b) 9.8 m/s2 (d) 87 m/s

2


Physics 1401

Chapter 8 Review

2. A wrench is used to tighten a nut as shown in

the figure. A 12-N force is applied 7.0 cm

from the axis of rotation. What is the torque

due to the applied force?

(a) 0.58 N • m

(b) 0.84 N • m

(c) 1.71 N • m

(d) 14 N • m

(e) 58 N • m

3. A string is tied to a doorknob 0.79 m from the

hinge as shown in the figure. At the instant

shown, the force applied to the string is 5.0 N.

What is the torque on the door?

(a) 3.3 N • m

(b) 2.2 N • m

(c) 1.1 N • m

(d) 0.84 N • m

(e) 0.40 N • m


6. A horizontal, 10-m plank weighs 100 N. It

rests on two supports that are placed 1.0

m from each end as shown in the figure.

How close to one end can an 800-N

person stand without causing the plank to

tip?

(a) 0 m (d) 0.6 m

(b) 0.2 m (e) 0.8 m

(c) 0.5 m

8. One end of a rope is tied to the handle of a

horizontally-oriented and uniform door. A force F is

applied to the other end of the rope as shown in the

drawing. The door has a weight of 145 N and is

hinged on the right. What is the maximum magnitude

of F at which the door will remain at rest?

(a) 145 N (d) 424 N

(b) 265 N (e) 530 N

(c) 381 N


10. 10. In the drawing shown, the large wheel has a radius of 8.5

m. A rope is wrapped around the edge of the wheel and a

7.6 kg-box hangs from the rope. A smaller disk of radius

1.9 m is attached to the wheel. A rope is wrapped around

the edge of the disk as shown. An axis of rotation passes

through the center of the wheel-disk system. What is the

value of the mass M that will prevent the wheel from

rotating?

(a) 1.7 kg (d) 34 kg

(b) 3.8 kg (e) 46 kg

(c) 12 kg

14. Consider four point masses located as shown in the

sketch. The acceleration due to gravity is the same

everywhere. What is the x coordinate of the center of

gravity for this system?

(a) 2.0 m (c) 3.0 m (e) 3.8 m

(b) 2.7 m (d) 3.3 m


17. Consider the following four objects:

a hoop; a solid sphere; a flat disk; a hollow sphere

Each of the objects has mass M and radius R. The axis of rotation passes through the

center of each object, and is perpendicular to the plane of the hoop and the plane of

the flat disk. Which object requires the largest torque to give it the same angular

acceleration ?

(a) the hoop (d) the hollow sphere

(b) the flat disk (e) both the solid and the hollow spheres

(c) the solid sphere

20. A massless frame in the shape of a square with 2-m sides

has a 1-kg ball at each corner. What is the moment of

inertia of the four balls about an axis through the corner

marked O and perpendicular to the plane of the paper?

(a) 4 kg • m2

(b) 8 kg • m2

(c) 10 kg • m2

(d) 12 kg • m2

(e) 16 kg • m2


22. The drawing shows the top view of a door that

is 2 m wide. Two forces are applied to the door

as indicated. What is the magnitude of the net

torque on the door with respect to the hinge?

(a) 0 N • m (c) 8.7 N • m (e) 26.0 N • m

(b) 5.0 N • m (d) 10.0 N • m

26. Three children are pulling on a rotatable platform on a

playground. The platform has a radius of 3.65 m. In the

picture, two children are pulling with equal forces of

40.0 N in an attempt to make the platform rotate

clockwise. The third child applies a force of 60 N as

shown. What is the net torque on the platform?

Note: “ccw” is counterclockwise and “cw” is

clockwise.

(a) 73 N • m, ccw (c) 511 N • m, ccw (e) 0 N • m

(b) 73 N • m, cw (d) 511 N • m, cw


28. A 45-N brick is suspended by a light string from a 2.0-kg

pulley. The brick is released from rest and falls to the

floor below as the pulley rotates through 5.0 rad. The

pulley may be considered a solid disk of radius 1.5 m.

What is the angular speed of the pulley?

(a) 7.3 rad/s (d) 15 rad/s

(b) 8.1 rad/s (e) 17 rad/s

(c) 9.4 rad/s

31. Consider the following three objects, each of the same mass and radius:

(1) a solid sphere (2) a solid disk (3) a hoop

All three are released from rest at the top of an inclined plane. The three objects

proceed down the incline undergoing rolling motion without slipping. In which order

do the objects reach the bottom of the incline?

(a) 1, 2, 3 (c) 3, 1, 2 (e) All three reach the bottom

(b) 2, 3, 1 (d) 3, 2, 1 at the same time.

34. A 2.0-kg solid cylinder of radius 0.5 m rotates at a rate of 40 rad/s about its

cylindrical axis. What power is required to bring the cylinder to rest in 10 s?

(a) 20 W (c) 160 W (e) 400 W

(b) 40 W (d) 200 W


38. A ceiling fan has five blades, each with a mass of 0.34 kg and a length of 0.66 m.

The fan is operating in its “low” setting at which the angular speed is 9.4 rad/s. If the

blades can be approximated as uniform thin rods that rotate about one end, what is

the total rotational kinetic energy of the five blades?

(a) 35 J (c) 23 J (e) 11 J

(b) 29 J (d) 17 J

41. What happens when a spinning ice skater draws in her outstretched arms?

(a) Her angular momentum decreases.

(b) Her angular momentum increases.

(c) Her moment of inertia decreases causing her to speed up.

(d) Her moment of inertia decreases causing her to slow down.

(e) The torque that she exerts increases her moment of inertia.

44. A 1500-kg satellite orbits a planet in a circular orbit of radius 6.2 × 106 m. What is

the angular momentum of the satellite in its orbit around the planet if the satellite

completes one orbit every 1.5 × 104 s?

(a) 3.9 × 106 kg • m

2/s (c) 6.2 × 10

8 kg • m

2/s (e) 2.4 × 10

13 kg • m

2/s

(b) 1.4 × 1014

kg • m2/s (d) 8.1 × 10

11 kg • m

2/s


50. A 3.0-kg ball moves in a straight line at 10 m/s as

shown in the figure. At the instant shown, what is

its angular momentum about the point P?

(a) 30 kg • m2/s

(b) 90 kg • m2/s

(c) 120 kg • m2/s

(d) 150 kg • m2/s

(e) zero kg • m2/s

Physics 1401

Chapter 9 Review

2. At standard temperature and pressure, carbon dioxide has a density of 1.98 kg/m3.

What volume does 0.85 kg of carbon dioxide occupy at standard temperature and

pressure?

(a) 0.43 m3 (c) 1.7 m

3 (e) 4.8 m

3

(b) 0.86 m3 (d) 2.3 m

3

3. What mass of water (at 4.0 °C) can be contained in a rectangular box whose

dimensions are 10.0 cm by 5.00 cm by 1.00 cm? The density of water at 4.0 °C is

1.000 × 103 kg/m3.

(a) 5.0 g (c) 25.0 g (e) 0.25 kg

(b) 10.0 g (d) 50.0 g


4. The density of iron is 7860 kg/m3. What is the mass of an iron sphere whose diameter

is 0.50 m?

(a) 123 kg (c) 514 kg (e) 4110 kg

(b) 164 kg (d) 983 kg

7. A solid cylinder has a radius of 0.051 m and a height of 0.0030 m. The cylinder is

composed of two different materials with mass densities of 1950 kg/m3 and 1470

kg/m3. If each of the two materials occupies an equal volume, what is the mass of the

cylinder?

(a) 8.4 × 10-2

kg (c) 6.5 × 10-2

kg (e) 4.2 × 10-2

kg

(b) 7.1 × 10-2

kg (d) 5.3 × 10-2

kg

Questions 15 and 16 pertain to the

situation described below: A swimming pool has the dimensions

shown in the drawing. It is filled with

water to a uniform depth of 8.00 m.

The density of water = 1.00 × 103 kg/m

3.


15. What is the total pressure exerted on the bottom of the swimming pool?

(a) 0.79 × 105 Pa (c) 1.80 × 10

5 Pa (e) 2.49 × 10

5 Pa

(b) 1.48 × 105 Pa (d) 1.97 × 10

5 Pa

16. What is the total force exerted on the bottom of the swimming pool?

(a) 2.40 × 107 N (c) 5.90 × 10

7 N (e) 8.40 × 10

7 N

(b) 5.40 × 107 N (d) 7.50 × 10

7 N

26. Which one of the following statements concerning a completely enclosed fluid is true?

(a) Any change in the applied pressure of the fluid produces a change in pressure that

depends on direction.

(b) The pressure at all points within the fluid is independent of any pressure applied to it.

(c) Any change in applied pressure produces an equal change in pressure at all points

within the fluid.

(d) An increase in pressure in one part of the fluid results in an equal decrease in pressure

in another part.

(e) The pressure in the fluid is the same at all points within the fluid.


27. A force of 250 N is applied to a hydraulic jack piston that is 0.01 m in diameter. If

the piston which supports the load has a diameter of 0.10 m, approximately how

much mass can be lifted by the Ignore any difference in height between the pistons.

(a) 255 kg (c) 800 kg (e) 6300 kg

(b) 500 kg (d) 2550 kg

28. In a car lift, compressed air with a gauge pressure of 4.0 × 105 Pa is used to raise a

piston with a circular cross-sectional area. If the radius of the piston is 0.17 m, what

is the maximum mass that can be raised using this piston?

(a) 530 kg (c) 9800 kg (e) 41 000 kg

(b) 3700 kg (d) 22 000 kg

30. 30. A 2-kg block displaces 10 kg of water when

it is held fully immersed. The object is then tied

down as shown in the figure; and it displaces 5

kg of water. What is the tension in the string?

(a) 10 N (d) 70 N

(b) 20 N (e) 100 N

(c) 30 N


32. Three blocks labeled A, B, and C are floating in

water as shown in the drawing. Blocks A and B have

the same mass and volume. Block C has the same

volume, but is submerged to a greater depth than the

other two blocks. Which one of the following

statements concerning this situation is false?

(a) The density of block A is less than that of block

C.

(b) The buoyant force acting on block A is equal to

that acting on block B.

(c) The volume of water displaced by block C is

greater than that displaced by block B.

(d) The buoyant force acting on block C is greater

than that acting on block B.

(e) The volume of water displaced by block A is

greater than that displaced by block B.

31. A balloon inflated with helium gas (density = 0.2 kg/m3) has a volume of 6 ⋅ 10

–3 m3.

If the density of air is 1.3 kg/m3, what is the buoyant force exerted on the balloon?

(a) 0.01 N (c) 0.8 N (e) 7.8 N

(b) 0.08 N (d) 1.3 N

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