PHy 101: Practice Exam #2
Chapters 6, 8, and 11 PLUS an inconvenient truth – global warming
1.) A snowboarder jumps off the lift. He sees a great run. Putting the snowboard on the ground, he runs at the
board and then jumps on the board to begin his descent. 5 kg = mass of snowboard, 65 kg is snowboarder’s
mass, initial running speed is 3 m/s.
What is the speed of the snowboarder and his board after he leaps onto it?
a.
b.
c.
d.
e.
2.78 m/s
1.5 m/s
5.56 m/s
29.4 m/s
210 m/s
2.) If the snowboard had a mass of 65 kg, what would you expect the final speed to be?
a)
b)
c)
d)
e)
equal to the initial speed
1/3 of the initial speed
two times the initial speed
½ of the initial speed
three times the initial speed
V 1 = 28 cm/s
V 2 = 12 cm/s
Before:
Collision:
After:
v1 = ?
v2 = ?
3.) Two equal mass balls move as shown above, Ball 1 is moving at 28 cm/s to the right and Ball 2 is moving at
12 cm/s to the right. What are the velocities of the two balls after an elastic collision?
a) Ball 1 moves at 28 cm/s to the right and Ball 2 moves at 12 cm/s to the right
b) Ball 1 moves at 12 cm/s to the right and Ball 2 moves at 28 cm/s to the left
c) Ball 1 moves at 28 cm/s to the left and Ball 2 moves at 12 cm/s to the right
d) Ball 1 moves at 12 cm/s to the right and Ball 2 moves at 28 cm/s to the right
e) The Balls will both come to a full and complete stop.
4.) Which of the following statements about momentum is TRUE?
a. If the momentum of a system is zero, nothing in the system is moving.
b. A small child falling to the cement floor will experience a larger momentum change from the fall if he
is wearing a padded diaper than if he is undressed.
c. When a ball falls from a shelf, its momentum increases and yet it does not violate the law of
conservation of momentum.
d. On the rotating table, our brave student volunteers were able to make more spins with their arms and
weights flung outward than when they pulled them in towards their bodies.
e. A paddle boat docked at the pier has a greater momentum than a skiff motoring about the bay.
Scene 1: Ball has total energy of 12 J.
Ball starts rolling down hill.
Scene 2: Ball rolling along flat plane.
Scene 3: The ball hits spring and compresses it.
The ball stops for an instant.
5.) Which of the following statements about the above scenes is TRUE?
a.
b.
c.
d.
e.
The ball has a potential energy of 10 J at the top of the hill.
The ball has potential and kinetic energy in scene 2.
The spring has potential energy of 5 J in scene 1.
The ball has kinetic energy in scene 3. (after it compresses the spring)
The spring has a potential energy of 12 J in scene 3.
6.) If a 0.08 kg hot wheel car starts at the top of a 2 meter hill, what is its speed at the top of the next 0.3 meter
hill? Neglect track friction.
a. 33,3 m/s
b. 2.42 m/s
c. 16.6 m/s
d. 4.08 m/s
e. 5.77 m/s
7.) How much power is required to lift a 50 Kg bell bar from the ground to shoulder height (1.7 m) in 0.2
seconds?
a. 4165 W
b. 425 W
c. 144.5 W
d. 167 W
e. 8330 W
8.) Which of the following are examples of potential energy.
a.
b.
c.
d.
e.
An unlit match has chemical potential energy.
A block of wood held out a window on the third story.
The top of a waterfall.
A fully charged battery.
All of the above are examples of potential energy.
9.) How much work must be done by my Bulldog Molly if she jumps over a garden fence that is 2.1 m high?
Molly has a mass of 18.2 Kg.
a.
b.
c.
d.
e.
178.4 J
38.2 J
40.1 J
374.6 J
187.3 J
10.) Choose the best definition of thermal energy listed below.
a.
b.
c.
d.
e.
The energetic jostling, in a purely random fashion, of atoms and molecules comprising a body.
The flow of jiggling atoms from one body to another.
A quantity that relates to the average kinetic energy of the molecules comprising a body.
The point when atoms and molecules have lost all their kinetic energy.
The amount of heat required to change the temperature of a body.
11.) Energy is neither ____________ nor ______________, it simply ____________its form.
a.
b.
c.
d.
e.
lost, found, slows down
destroyed, created, changes
large, small, shrinks
created, destroyed, loses
none of the above
12.) You place your hand on a window on a cold winter's day and your hand becomes cold. This is an example
of ________________.
a. thermal conduction
b. thermal convection
c. thermal radiation
d. thermal expansion
e. none of the above
13.) The greenhouse effect is predominantly caused by large concentrations of _________ in the atmosphere
caused by emissions from ________________ and power plants, and excessive deforestation of the planet.
a. CO2, cars
c. S, furnaces
e. H, electric heaters
b. O2, cows
d. Fe, vehicles
14.) The amount of thermal energy required to raise 4 kg of gasohol from 297 K to 332 K is _________. The
specific heat capacity of gasohol is c = 3140 J/kg K.
a.
b.
c.
d.
e.
4,170,000 J
440,000 J
3,730,000 J
220,000 J
4,400,000 J
15.) If your instructor were to place a 0.5 m bar of aluminum in a flame and then after a period of time the
length was measured to be 0.5005 m, what increase in temperature did the bar undergo while being heated?
[(aluminum) = 24x10-6(oC)-1]
a. 4 oC
b. 21.6 oC
c. 41.7 oC
d. 834 oC
e. 41708 oC