Transcript Chapter7Q

Chapter 7
Energy
1. How much work is done on a
200-kg crate that is hoisted 2 m in
a time of 4 s?
a.
b.
c.
d.
400 J
1000 J
1600 J
4000 J
2. How much power is required to
raise a 200-kg crate a vertical distance
of 2 m in a time of 4 s?
a.
b.
c.
d.
400 W
1000 W
1600 W
4000 W
3. Where is the maximum
potential energy on the track?
• a. top
• b. middle
• c. bottom
a
b
c
4. When work is done twice as quickly,
then the power expended is
a. half.
b. the same.
c. twice.
d. 4 times as much.
5. If a charging elephant has kinetic
energy, it must also have
a.
b.
c.
d.
potential energy.
momentum.
acceleration.
All of these.
6. A model airplane moves twice as fast as
another identical model airplane. Compared
with the kinetic energy of the slower
airplane, the kinetic energy of the faster
airplane is
a.
b.
c.
d.
the same for level flight.
twice as much.
4 times as much.
more than 4 times as much.
7. A skateboarder weighing 100N moves
10m in 5 sec. How much power is
required?
a. 1000 J
b. 250 J
c. 200 J
d. 5000 J
8. A model airplane moves 3 times as fast
as another identical model airplane.
Compared with the kinetic energy of the
slower airplane, the kinetic energy of the
faster airplane is
a.
b.
c.
d.
the same for level flight.
twice as much.
4 times as much.
9 times as much.
9. A dog and a mouse run down the
road with the same KE. The faster
moving one is the
a. dog.
b. mouse.
c. Both run at the same speed.
d. Can’t say.
10 A 1-kg ball has twice the speed as a
2-kg ball. Compared with the 1-kg ball,
the 2-kg ball has
a.
b.
c.
d.
the same kinetic energy.
1/2 the kinetic energy.
4 times the kinetic energy.
more than 4 times the kinetic energy.
11. A shiny sports car at the top of a vertical
cliff has a potential energy of 100 MJ relative to
the ground below. Unfortunately, a mishap
occurs and it falls over the edge. When it is
halfway to the ground, its kinetic energy is
a. 25 MJ.
b. 50 MJ.
c. about 100 MJ.
d. more than 100 MJ.
12. True or False the force required is the
same to lift each to the top?
13. If the weight is 5m above the spike being
driven what is its velocity when it strikes the
spike.
a)
b)
c)
d)
5m/s
10 m/s
50 m/s
100 m/s
5m