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practiceTestch3withProjectileMotion

Modified True/False
Indicate whether the sentence or statement is true or false.  If false, change the identified word or phrase to make the sentence or statement true.
 

 1. 
Hunters experience a “kick” when they fire a 12 gauge shotgun. This is due to the backward acceleration caused by the reaction force called recoil. _________________________

 

 2. 
As a skateboarder increases her speed (or velocity) from 2 m/s to 4 m/s, she also increases her inertia. _________________________

 

 3. 
“For every action there is an equal and opposite reaction” is a statement of Newton’s first law of motion. _________________________

 

 4. 
Units for measuring impulse, newton-seconds, are equivalent to kilogram-meters per second, units for measuring momentum. _________________________

 

 5. 
As the speed of a ball rolling on the floor decreases, its potential energy decreases. _________________________

 

 6. 
The path followed by a projectile whose motion is affected only by gravity is a hyperbola. _________________________

 

 7. 
The horizontal distance a projectile travels is called its trajectory. _________________________

 

 8. 
The time a golf ball is in the air and its height are greatest when the ball is fired at an angle of 45º. _________________________

 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 9. 
As the speed of a rolling ball is increasing, the increasing speed is accompanied by:
a.
increasing momentum.
b.
increasing inertia.
c.
decreasing momentum.
d.
both increasing inertia and momentum.
 

 10. 
“Forces occur in pairs” is another way of stating Newton’s:
a.
first law of motion.
b.
second law of motion.
c.
third law of motion.
d.
universal law of motion.
 

 11. 
Even though every action force has an equal but opposite reaction force, they do not cancel one another and motion may still occur because the:
a.
action and reaction forces are applied to the same object.
b.
action and reaction forces are applied to different objects.
c.
two forces have different magnitudes.
d.
two forces have equal magnitudes.
 

 12. 
To calculate momentum:
a.
add the mass of an object to its inertia.
b.
add the mass of an object to its velocity.
c.
multiply the mass of an object by its inertia
d.
multiply the mass of an object by its velocity.
 

 13. 
The impulse applied to an object is equal to the change in the object’s:
a.
mass.
b.
inertia.
c.
momentum.
d.
height.
 

 14. 
To increase the final momentum of a racquetball, the player should:
a.
swing the racquet as fast as possible.
b.
follow through when hitting the ball.
c.
increase contact time with the ball.
d.
All of the above
 

 15. 
The impulse necessary to change the momentum of a 20-kilogram object by 5 kg·m/sec is:
a.
4 kg·m/sec.
b.
5 kg·m/sec.
c.
15 kg·m/sec.
d.
100 kg·m/sec.
 

 16. 
A rocket can fly into space because:
a.
the exhaust gases push against the ground and the ground, in turn, pushes the rocket.
b.
the rocket pushes on exhaust gases and the exhaust gases push back on the rocket.
c.
as the fuel burns, the rocket’s mass decreases reducing the force of gravity on the rocket.
d.
the launch pad absorbs momentum that it imparts to the rocket.
 

 17. 
The momentum of a 2000 kilogram car traveling at 20 meters per second is:
a.
0 kg·m/sec.
b.
0.001 kg·m/sec.
c.
100 kg·m/sec.
d.
40,000 kg·m/sec.
 

 18. 
If a 40,000 kilogram rocket were traveling from its launch pad at a speed of 150 meters per second, 800 kilograms of gases would be expelled from the rocket at a speed of about:
a.
0.33 m/sec.
b.
270 m/sec.
c.
7,500 m/sec.
d.
21,000 m/sec.
 

 19. 
Air bags reduce injury in automobile accidents by:
a.
reducing the time of collision.
b.
reducing the change in momentum.
c.
increasing the applied force.
d.
increasing the time of collision.
 

 20. 
Ken rolls a 7-kilogram bowling ball so slowly that it stops before it moves through all of the pins. The impulse necessary to stop this bowling ball rolling at 2 meters per second is ____ newton-seconds.
a.
3.5
b.
5.0
c.
7.0
d.
14
 

 21. 
Kiki accidentally nudges a glass tumbler with her elbow and it falls toward a hard, ceramic tile floor. As a soccer player, Kiki reacts by catching the glass with her foot and lowering it to the floor, preventing the glass from breaking. Her action prevents the breakage because:
a.
the change in momentum is smaller when Kiki catches and lowers the glass to the floor.
b.
the impulse is smaller when Kiki catches the glass and lowers it to the floor.
c.
the time interval for stopping is greater when Kiki catches the glass with her foot.
d.
a larger force is exerted by Kiki’s foot to stop the glass in time.
 

 22. 
While standing on a stationary skateboard, Jolene tosses a heavy ball horizontally toward one end of her skateboard. The skateboard moves. Assuming there is no friction in the system when the ball is tossed, which statement about the momentum of the heavy ball is INCORRECT?
a.
The ball’s momentum is equal in size to the momentum of Jolene and her skateboard.
b.
The ball’s momentum plus the momentum of Jolene and her skateboard equals zero.
c.
The ball’s momentum has increased because Jolene has tossed it.
d.
The directions of the ball’s momentum and Jolene’s momentum are the same.
 

 23. 
Alex hits a line drive directly up the middle which leaves his bat traveling at 250 meters per second. If the pitcher has thrown the 0.15-kilogram baseball to Alex at 140 meters per second, what is the impulse applied to the baseball by Alex?
a.
17 newton-seconds
b.
21 newton-seconds
c.
38 newton-seconds
d.
59 newton-seconds
 

 24. 
A 0.15-kilogram baseball thrown at a speed of 50 meters per second and a 7.25-kilogram bowling ball rolling at 2 meters per second are both stopped in 0.2 seconds.
a.
The baseball is stopped with less force because it has less inertia.
b.
The baseball is stopped with less force because it has less momentum.
c.
The bowling ball is stopped with less force because it has less momentum.
d.
The bowling ball is stopped with less force because it has less inertia.
 

 25. 
What impulse must be applied to a 3-kilogram object to give it 150 joules of kinetic energy?
a.
21 newton-seconds
b.
30 newton-seconds
c.
50 newton-seconds
d.
3,000 newton-seconds
 

 26. 
The skateboard on which you are standing moves as one of your feet pushes on the ground because the force you apply on the skateboard:
a.
equals the force applied to you by the skateboard.
b.
is larger than the force applied to you by the skateboard.
c.
equals the force applied by the ground on the skateboard.
d.
is larger than the force applied by the ground on the skateboard.
 

 27. 
Jumping on a trampoline, Jeffrey can easily soar 6 feet into the air but can only jump 2 feet from the blacktop of the driveway basketball court because the:
a.
court applies a larger impulse.
b.
trampoline applies a larger impulse.
c.
court applies less force on Jeffrey.
d.
trampoline applies more force on Jeffrey.
 

 28. 
Energy that is stored due to the position of an object may be called ____ energy.
a.
kinetic
b.
potential
c.
radiant
d.
nuclear
 

 29. 
A 20-kilogram object falls 2.0 meters to the floor. At what point in its fall does the kinetic energy of a body equal its potential energy?
a.
At all points of the fall
b.
Very nearly at the top of the fall
c.
Halfway to the floor
d.
Just the instant before it hits the floor
 

 30. 
An object falls without friction near Earth’s surface. The loss of its potential energy is equal to its:
a.
loss of height.
b.
loss of mass.
c.
gain in kinetic energy.
d.
gain in velocity.
 

 31. 
The ability to cause change is defined as:
a.
force and is measured in newtons.
b.
power and is measured in watts.
c.
energy and is measured in joules.
d.
impulse and is measured in newton-seconds.
 

 32. 
Energy may be measured using units of:
a.
watts.
b.
newtons.
c.
joules.
d.
newtons per second.
 

 33. 
In science, work is defined as:
a.
the mass of an object multiplied by its acceleration.
b.
the mass of an object multiplied by the force required to move it.
c.
force multiplied by the distance moved in a direction perpendicular to the force.
d.
force multiplied by the distance moved in the same direction as the force.
 

 34. 
Potential energy increases as a marble:
a.
slows rolling up an incline.
b.
increases speed down an incline.
c.
rolls at uniform speed on a level table.
d.
sits motionless on the floor.
 

 35. 
Calculate the work done to lift a barbell weighing 100 newtons a distance of 1.5 meters.
a.
0.015 joules
b.
15 joules
c.
66.7 joules
d.
150 joules
 

 36. 
Jonah is pushing his younger sister, Jessica, on a swing. If Jessica weighs 350 newtons, how much higher above the ground must Jonah push her to increase her potential energy by 525 joules?
a.
0.67 meters
b.
1.5 meters
c.
3.6 meters
d.
5.4 meters
 

 37. 
A basketball player who weighs 600 newtons jumps 0.5 meters vertically off the floor.What is her kinetic energy the instant before hitting the floor?
a.
30 joules
b.
60 joules
c.
300 joules
d.
600 joules
 

 38. 
Lifting a 70-kilogram barbell 2.0 meters above the floor increases its potential energy by about:
a.
35 joules.
b.
140 joules.
c.
350 joules.
d.
1,400 joules.
 

 39. 
The amount of mechanical kinetic energy possessed by a 0.25-kilogram ball rolling at a speed of 2.5 meters per second is ____ joules.
a.
0.31
b.
0.63
c.
0.78
d.
1.6
 

 40. 
As the speed of a moving object doubles, the amount of mechanical kinetic energy that it possesses:
a.
increases by two times.
b.
increases by four times.
c.
decreases by two times.
d.
decreases by four times.
 

 41. 
Jonah is pushing his younger sister, Jessica, on a swing. If Jessica weighs 35 kilograms, how much higher above the ground must Jonah push her to increase her potential energy by 525 joules?
a.
0.67 meters
b.
1.5 meters
c.
3.6 meters
d.
5.4 meters
 

 42. 
Shawna, who weighs 54 kilograms, is roller blading on a level surface. If she is rolling at 12 meters per second, to what height would she roll up an incline before stopping? (Assume there is no friction.)
a.
0.61 meters
b.
1.2 meters
c.
7.3 meters
d.
15 meters
 

 43. 
When the brakes are fully applied, compared to the distance required to stop a car going 30 miles per hour, the distance needed to stop a car going 90 miles per hour is:
a.
3 times as great.
b.
6 times as great.
c.
9 times as great.
d.
the same.
 

 44. 
All of the following may be the result of an inelastic collision EXCEPT:
a.
permanent change in the shape of the colliding bodies.
b.
kinetic energy released as sound.
c.
colliding bodies stick to one another.
d.
zero loss of kinetic energy.
 

 45. 
Which of the following situations is an example of a mostly elastic collision?
a.
Two billiard balls collide and bounce off each other.
b.
Two train card collide and stick together.
c.
When a soft piece of clay falls onto the floor, its shape flattens.
d.
A glass falls off the table and breaks.
 

 46. 
When two objects hit each other, a(n) ____ occurs.
a.
joule
b.
impulse
c.
collision
d.
momentum
 

 47. 
A boy whose mass is 40 kilograms runs at 5 meters per second and jumps onto a 10-kilogram stationary sled. The boy slides on the sled over a horizontal, frictionless surface at a speed of:
a.
2 m/sec.
b.
4 m/sec.
c.
5 m/sec.
d.
10 m/sec.
 

 48. 
What braking force is needed to stop a 1,000-kilogram car moving at 10 m/sec in a time of 1 seconds?
a.
1 newton
b.
10 newtons
c.
100 newtons
d.
10,000 newtons
 

 49. 
A 2-kilogram piece of clay moving at 4 m/sec strikes and sticks to a second 4-kilogram piece of clay moving at 1 m/sec in the opposite direction. Calculate the speed of the combined piece of clay.
a.
1 m/sec
b.
2 m/sec
c.
4 m/sec
d.
6 m/sec
e.
2/3 m/sec
 

 50. 
The parabolic path followed by a projectile is referred to as the:
a.
range.
b.
trajectory.
c.
circumference.
d.
ellipse.
 

 51. 
A golf ball will have the greatest range when it is hit an angle of:
a.
30º.
b.
45º.
c.
60º.
d.
90º.
 

 52. 
The distance a projectile travels is dependent upon:
a.
air resistance.
b.
launch angle.
c.
launch speed.
d.
All of the above
 

 53. 
The distance a projectile travels horizontally in the air may be called its:
a.
trajectory.
b.
range.
c.
parabola.
d.
height.
 

 54. 
If a ball thrown horizontally with a speed of 15 meters per second travels for 5 seconds before hitting the ground, its range after 4 seconds would be about ____ meters.
a.
15
b.
39
c.
60
d.
153
 

 55. 
Of the following, the one that would NOT be considered a projectile is a:
a.
crow flying between trees.
b.
football thrown by a high school quarterback.
c.
tennis ball hit by a star tennis player.
d.
fox jumping over a wall.
 

 56. 
Jennifer and Tamar throw a snowballs at the same time horizontally from a height of 1.5 meters. Jennifer throws hers at a speed of 6.0 meters per second. If Tamar throws hers at 12 meters per second, her snowball will:
a.
travel the same distance as Jennifer’s before hitting the ground.
b.
hit the ground later than Jennifer’s.
c.
travel the half the distance as Jennifer’s before hitting the ground.
d.
hit the ground at the same time as Jennifer’s.
 

 57. 
The golf ball that will travel farthest is one hit at an angle of:
a.
20º.
b.
30º.
c.
40º.
d.
60º.
 

 58. 
If a ball thrown horizontally with a speed of 15 meters per second travels for 5 seconds before hitting the ground, its horizontal speed after 4 seconds is ____ m/sec.
a.
15
b.
39
c.
60
d.
75
 

 59. 
A projectile launched at a speed of 35 meters per second will have the greatest horizontal speed when launched at an angle of:
a.
20º.
b.
30º.
c.
45º.
d.
60º.
 

 60. 
ch3projmotionpracti_files/i0620000.jpg

This toy bird balances on the tip of the finger because:
a.
the torque caused by the force of the bird’s weight is greater at the beak than the tail.
b.
the center of gravity is in line with the finger.
c.
the bird’s weight is outside its area of support.
d.
It can’t possibly balance like that. It must be glued onto the finger.
 

Completion
Complete each sentence or statement.
 

 61. 
As Maria steps from a small rowboat towards a pier, the boat moves away from the pier. Maria falls into the water. She is a “victim” of the law of conservation of ____________________.
 

 

 62. 
Alicia is asked to calculate the change in momentum that occurs as she stops her bicycle. This is equivalent to the ____________________ applied to the bicycle.
 

 

 63. 
The expression ch3projmotionpracti_files/i0660000.jpg represents _________________________.
 

 

 64. 
The expression mgh represents _________________________ energy.
 

 

 65. 
The kinetic energy of an object depends upon two things: ____________________ and ____________________.
 

 

 66. 
“Energy can never be created or destroyed, just transformed from one form to another” is a statement of the law of ______________________________ (three words).
 

 

 67. 
The expression ch3projmotionpracti_files/i0700000.jpg represents ____________________ energy.
 

 

 68. 
The path that a projectile follows after being fired is called its ____________________.
 

 

 69. 
The vertical and horizontal components of a projectiles motion are ____________________ of one another.
 

 

 70. 
If a ball, fired as a projectile, travels 30 meters when it leaves the ground at a 20º angle, it will travel the same distance when fired at an angle of ____________________ degrees.
 

 

Short Answer
 

 71. 
A speeding truck makes contact with a bug on its windshield. Compare the force that the bug exerts on the truck to the force the truck exerts on the bug.
 

 72. 
When you push on your friend who is seated in a wagon, the wagon moves. According to Newton’s 1st law of motion, the force you apply to your friend is equal but opposite to the force your friend applies to you. Explain why the two equal and opposite forces do not cancel one another with no resulting motion. Tell what force does cause the motion.
 

 73. 
As a tennis player, golfer, baseball player or soccer player you might be told by your coach to “follow through” when striking the ball. Explain why.
 

 74. 
A ball is thrown from position (1) to a height of 5 meters above at position (2), giving the ball potential energy. The ball then falls to position (3). Assuming there is no loss of energy due to friction:
ch3projmotionpracti_files/i0780000.jpg
A. Name the height at which the kinetic energy of the ball would be exactly the same its potential energy?
B. Compare the potential energy at (3) to the kinetic energy at (2).
C. Compare the kinetic energy at (1) to the potential energy at (2).
 

 75. 
Name three factors that can affect the range of a projectile.
 

 76. 
Of the following flying objects, list those that are projectiles:
a. A jet plane just after take-off
b. A baseball hit by a star baseball player
c. A free-throw after being released by a basketball player
d. A rock thrown from a bridge into a river below
e. A bird flying between trees
f. A young woman diving from the starting block into a swimming pool
 

 77. 
Projectile motion may be separated into two components, vertical and horizontal. In addition to the difference in their directions, state another difference between these motion vectors.
 

Problem
 

 78. 
Calculate the momentum of a 30-kilogram cart moving at a speed of 2.0 meters per second.
 

 79. 
While sitting motionless on a 10-kilogram, friction-free wagon, 75-kilogram “Bozo, the human target” catches an 8-kilogram cannonball moving at 15 meters per second. After catching the cannonball, at what speed do Bozo, the wagon and cannonball move?
 

 80. 
Calculate the size of the impulse that must be applied to stop a 200-kilogram wagon rolling on a flat path at a speed of 4.5 meters per second.
 

 81. 
Calculate the speed of a 0.25-kilogram water balloon propelled by a water balloon launcher applying an average force of 20 newtons for 0.75 seconds.
 

 82. 
Calculate the maximum height a 0.75-kg ball will rise if it is kicked straight up with an initial speed of 17 meters per second.
 

 83. 
A bowling ball rolls off a horizontal loading platform 2.0 meters high with a speed of 3.0 m/sec. How long will it take to hit the ground?
 

 84. 
A quarterback throws a football, giving it a vertical velocity of 9.2 meters per second and a horizontal velocity of 25.4 meters per second. Calculate the vertical and horizontal components of the football’s velocity after 1.00 second.
 

 85. 
A rocket is fired into the air with vertical velocity of 58.8 meters per second.and a horizontal velocity of 21.3 meters per second. Assuming the rocket is in free-fall, calculate the range of the rocket.
 

Essay
 

 86. 
If you exert the same force on Earth that Earth exerts on you, why doesn’t Earth move up to meet you when you jump off its surface?

ch3projmotionpracti_files/i0920000.jpg
 

 87. 
A 20-gram ball of clay strikes a wooden block (pictured in the diagram) at a speed of 10 cm/sec and sticks to the block. The block wiggles but does not tip over. A 20-gram “bouncy ball” traveling at 10 cm/sec strikes the same block and bounces off in the direction from which it came. This time, the block tips over. Explain why.

ch3projmotionpracti_files/i0930000.jpg
 

 88. 
Explain the statement, “The horizontal and vertical components of a projectile’s velocity are independent of each other.”
 



 
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