Use the table to answer the question.

Object Mass (grams)
table tennis ball 2.7
baseball 147.0
small rock 248.2
penny 2.5
A student drops the four objects listed from a height of 2 meters into a bucket of water. Which object will have the greatest kinetic energy?
Responses:
1) table tennis ball
2) baseball
3) penny
4) small rock

1 answer

To determine the object with the greatest kinetic energy, we need to calculate the kinetic energy of each object using the formula:

Kinetic Energy = 1/2 * mass * velocity^2

Since the objects are dropped from a height of 2 meters, we can determine their velocity using the equation:

velocity = sqrt(2 * gravity * height)

where gravity is the acceleration due to gravity (approximately 9.8 m/s^2).

Let's calculate the kinetic energy for each object:

1) table tennis ball:
mass = 2.7 grams = 0.0027 kg
velocity = sqrt(2 * 9.8 * 2) = 6.26 m/s
Kinetic Energy = 1/2 * 0.0027 * (6.26)^2 = 0.042 J

2) baseball:
mass = 147.0 grams = 0.147 kg
velocity = sqrt(2 * 9.8 * 2) = 6.26 m/s
Kinetic Energy = 1/2 * 0.147 * (6.26)^2 = 0.344 J

3) penny:
mass = 2.5 grams = 0.0025 kg
velocity = sqrt(2 * 9.8 * 2) = 6.26 m/s
Kinetic Energy = 1/2 * 0.0025 * (6.26)^2 = 0.039 J

4) small rock:
mass = 248.2 grams = 0.2482 kg
velocity = sqrt(2 * 9.8 * 2) = 6.26 m/s
Kinetic Energy = 1/2 * 0.2482 * (6.26)^2 = 0.487 J

Therefore, the object with the greatest kinetic energy is the small rock, with a kinetic energy of 0.487 Joules. Answer: 4) small rock