Question

Question 9
A rock is thrown straight up into the air. While it rises and falls, its kinetic energy ...

a
increases steadily
b
remains constant
c
increases then decreases
d
decreases then increases
Question 10
What is the potential energy of an object that has a mass of 115 kg and is 6 meters high?



a
130.8 J
b
1380 J
c
676.2 J
d
6762 J
Question 11
Simple machines can multiply:

a
forces only
b
energy only
c
power only
d
forces and energy
Question 12
Energy due to motion is called _____________energy.

a
kinetic
b
stored
c
gravitational
d
potential
Question 13
What is the kinetic energy of a 200 kg object that is moving at a velocity of 15 m/s?

\large KE=\frac{1}{2}mv^2

a
3000 J
b
2150 J
c
215 J
d
22,500 J
Question 14
True or False

According to the Law of Conservation of Energy, energy can neither be created nor destroyed.

True
False
Question 15
Which object would have the most potential energy?

PE = mgh

g = 9.8 m/s2

a
a 10 kg dog sitting on the ground
b
a 0.25 kg book sitting on a table 2 meters tall
c
a 2 kg bottle of soda on a shelf 2.5 meters tall
d
a 5 kg bowling ball in a person's hand at 0.75 meter

Answer 1

Q9: d — decreases then increases (kinetic energy falls as it rises, is zero at the top, then increases as it falls)

Q10: d — 6762 J
Calculation: PE = mgh = 115 kg × 9.8 m/s² × 6 m = 6762 J

Q11: a — forces only (simple machines can multiply force at the expense of distance; they do not multiply energy)

Q12: a — kinetic

Q13: d — 22,500 J
Calculation: KE = 1/2 mv² = 0.5 × 200 kg × (15 m/s)² = 100 × 225 = 22,500 J

Q14: True — energy can neither be created nor destroyed (conservation of energy)

Q15: c — a 2 kg bottle at 2.5 m (PE = 2 × 9.8 × 2.5 = 49 J; this is the largest of the choices)