Name (printed) _______________________________
First Day Stamp
For each of the following questions, give clear and complete evidence for your choice in the space
provided.
1. _____
Which of the following has the largest momentum relative to the Earth?
a. a tightrope walker crossing Niagara Falls
c. a pickup truck speeding along a highway
b. a Mack truck parked in a parking lot
d. a dog running down the street
2. _____
Compared to falling on a wooden floor, a wine glass may not break when it falls to a carpeted floor
because of the
a. smaller impulse
b. longer time to stop.
c. both of these
d. neither of these.
3. _____
Compared to the force that brings a small car to a stop, the force required to bring a heavy truck traveling
at the same speed to a stop
a. is less
b. is more
c. may be less and may be more.
4. _____
Why is it safer to hit your head on a padded dashboard than on an unpadded dashboard?
a. The change in momentum is smaller
c. The impulse is smaller
b. The impulse time is longer
d. The acceleration is higher
5. _____
A 15.0 N force acts on a 2.0 kg mass for 5.0 seconds. How much does the momentum of the object
change?
a. 6 kg-m/s
b. 38 kg-m/s
c. 75 kg-m/s
d. 150 kg-m/s
6. _____
A mass of 2 kg is at rest on a frictionless horizontal surface. A constant force of 2 N is applied to the
mass for 3 s and is then removed. What is the speed of the mass after 6 s?
a. 1 m/s
b. 3 m/s
c. 6 m/s
d. 12 m/s
e. 24 m/s
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QUESTIONS AND PROBLEMS
IMPULSE AND MOMENTUM
Do the following questions and problems from the Giancoli book in the space provided on the following two pages.
Pages 187 – 192 Questions 6, 7, 9;
Problems 15, 17, 18, 20, 75
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For each of the following questions, give clear and complete evidence for your choice in the space
provided.
1. _____
A firecracker is placed in the midst of a motionless cluster of billiard balls on a table. When the
firecracker explodes, the balls scatter in all directions. The total momentum of the balls immediately
after the explosion is
a. more than before the explosion
c. the same as before the explosion
b. less than before the explosion
d. cannot tell from this information
2. _____
Two objects collide and one is initially at rest. After the collision, it is possible for:
a. both to be moving
d. either “a” or “b”
b. one to be moving
e. either “a” or “c”
c. both to be at rest
f. either “a,” “b,” or “c”
3. _____
Mighty Matt weighs 800 N and is running down the football field at 4 m/s. Speedy Gonzales weighs only
400 N but runs at 8 m/s, while Ponderous Poncho weighs 1600 N and runs only 2 m/s. In an attempt at a
tackle who will be more effective in stopping Matt?
a. Speedy Gonzales
b. Ponderous Poncho
c. Both the same
4. _____
In which collision will Mighty Matt be hurt more?
a. Speedy Gonzales
b. Ponderous Poncho
5. _____
c. Both the same
A rifle recoils from firing a bullet. The speed of the rifle’s recoil is small because the
a. force against the rifle is smaller than against the bullet. c. rifle has much more mass than the bullet.
b. momentum is mainly concentrated in the bullet
d. momentum of the rifle is smaller.
6. _____A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish swimming toward it at
4 m/s. The speed of the larger fish after lunch is
a. 19 m/s
b. 16 m/s
c. 15 m/s
d. 12 m/s
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QUESTIONS AND PROBLEMS
CONSERVATION OF MOMENTUM
Do the following questions and problems from the Giancoli book in the space provided on the following two pages.
Pages 187 – 192 Questions 3, 4, 5;
Problems 4, 6, 8, 12, 13, 66
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QUESTIONS AND PROBLEMS
CONSERVATION OF MOMENTUM IN TWO DIMENSIONS
Do the following problems from the Giancoli book in the space provided on the next two pages.
Pages 190 – 192
Problems 40, 41, 42, 78
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LAB
THE BALLISTIC PENDULUM
This classic case of combining both the law of
conservation of energy and the law of conservation of
momentum is now possible as a lab using the steel
ball shot from the mini projectile launcher into a
pendulum catcher. Let’s break down the process –
step by step:
INTRODUCTION
It might seem like you would need a “high tech”
method to measure the speed of a bullet, but you can
do it easily with a simple distance measurement and
two simple mass measurements. It’s been done
routinely for over a century with the ballistic
pendulum (see Figure 1). This device is nothing
more than a block of wood suspended by strings so
that it is free to swing back and forth and is large
enough to capture and fully contain a high-speed
bullet. It is quite accurate, safe, and is a very elegant
example of the power of both the law of conservation
of energy and the law of conservation of momentum.
To use the ballistic pendulum, a bullet is fired into
the block of wood and the block moves forward (see
Figure 2) and up (see Figure 3). Because no
momentum is lost in collisions, the momentum of the
block and bullet after the collision is equal to the
momentum of the bullet before the collision.
Additionally, because of energy conservation, the
gravitational potential energy of the block at its
highest point is equal to its kinetic energy at the
lowest point, (after the bullet has entered the block).
You can use the height that the block rises (easily
measured with a meter stick) to calculate the increase
in gravitational potential energy for the block and
bullet at their highest point. Then you can use this to
find the speed of the block and its momentum at their
lowest point. Finally, you can use the momentum of
the block after it is hit to find the original speed of
the bullet. Now that is impressive! I did this as a
demonstration at Tam for many years until it was
deemed too dangerous (in 2006).
Action
Reason
Measure the maximum
height of the ballistic
pendulum after it has
been struck by the bullet.
Needed in order to
calculate the increase in
gravitational
potential
energy of the ballistic
pendulum.
Calculate the increase in
gravitational
potential
energy of the ballistic
pendulum after it has
been struck by the bullet.
It will be the same as the
kinetic energy of ballistic
pendulum after it has
been struck by the bullet.
Conservation of Energy
is applied here.
Determine the speed of
the ballistic pendulum
just after it has been
struck by the bullet.
Needed to calculate the
momentum
of
the
ballistic pendulum just
after it has been struck
by the bullet.
Calculate the momentum
of the ballistic pendulum
just after it has been
struck by the bullet.
It will be the same as the
momentum of the bullet
just before it strikes the
ballistic
pendulum.
Conservation
of
Momentum is applied
here.
Calculate the speed of
the bullet from its
momentum.
This is the goal of the
process.
Figure 2: Pendulum moving forward after
receiving the projectile.
Figure 1: Ballistic Pendulum
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Figure 3: Pendulum rising after receiving the
projectile.
PURPOSE
To use the laws of Conservation of Energy and Conservation of Momentum to calculate the speed of a projectile.
PROCEDURE (PART 1)
Fire the projectile launcher vertically into the air several times, measuring the maximum height of the metal ball
with a ruler each time. This should be done on the long range setting (three clicks).
DATA (PART 1)
Maximum Height
of Ball (m)
Average maximum height of the ball: ________
QUESTIONS/CALCULATIONS (PART 1) (SHOW ALL WORK CAREFULLY)
1.
Use the maximum height of the ball to calculate its initial speed. This will be the known projectile speed that
will be used for comparison in the second part of the lab.
PROCEDURE (PART 2)
1.
Determine the mass of the ball and the catcher and the height of the bottom of the catcher above the lab
table.
2.
Attach a thread from the ball catcher to the Velcro assembly on the base of the launcher.
3.
With the launcher on the long-range setting, fire a test shot to see how far the thread gets pulled out. Pull two
centimeters of thread back through the Velcro, leaving the rest of the thread slack. This reduces the effect of
friction throughout the trials.
4.
Fire the ball into the pendulum. After the shot, pull the pendulum back until it is taut and measure the
change in height for the pendulum.
5.
Repeat five times.
DATA (PART 2)
Mass of ball (kg): ________
Mass of catcher (kg): ________
Height change of
Catcher (m)
Average change in height of the catcher: ________
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Height above table (m): ________
QUESTIONS/CALCULATIONS (PART 2) (SHOW ALL WORK CAREFULLY)
1.
Use your data and the steps discussed on page 9 to determine the speed of the steel ball as it left the
launcher. There are several steps here. Please indicate each step and explain why it is necessary.
2.
Calculate the percent difference between the speed of the steel ball found in part 1 and its speed found in
Part 2.
3.
Calculate the KE of the steel ball before it strikes the catcher. Then use the KE of the catcher and ball after
the ball strikes it to calculate the percentage KE lost in the collision. Explain where lost kinetic energy went.
4.
Pat and Sam are hanging from the ceiling by two ropes attached to them and they push off each other. Pat
has a mass of 110 kg, and Sam has a mass of 73 kg. Following the push, Pat swings upward to a height of
0.30 m above his starting point. To what height above his starting point does Sam rise?
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QUESTIONS AND PROBLEMS
COMBINING ENERGY AND MOMENTUM
Do the following problems from the Giancoli book in the space provided on the next two pages.
Pages 190 – 192
Problems 32, 34, 35, 70, 71, 78
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QUESTIONS AND PROBLEMS
CONSERVATION OF ANGULAR MOMENTUM
Do the following questions and problems from the Giancoli book in the space provided on the next two pages.
Pages 218 - 225
Questions 15, 20, 22, 24 Problems 56, 60, 61a, 82
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