Question

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? (1 point)

Answer 1

To determine which object will have the greatest kinetic energy when dropped from a height, we can use the formula for gravitational potential energy (which converts to kinetic energy when the object falls):

\[ KE = mgh \]

where:
- \( KE \) = kinetic energy,
- \( m \) = mass of the object (in kilograms),
- \( g \) = acceleration due to gravity (approximately \( 9.81 \, m/s^2 \)),
- \( h \) = height (in meters).

We need to convert the mass of each object from grams to kilograms (1 gram = 0.001 kilograms) before substituting them into the formula.

1. Table tennis ball:
- Mass = 2.7 grams = 0.0027 kg
- \( KE = 0.0027 \times 9.81 \times 2 \)

2. Baseball:
- Mass = 147.0 grams = 0.147 kg
- \( KE = 0.147 \times 9.81 \times 2 \)

3. Small rock:
- Mass = 248.2 grams = 0.2482 kg
- \( KE = 0.2482 \times 9.81 \times 2 \)

4. Penny:
- Mass = 2.5 grams = 0.0025 kg
- \( KE = 0.0025 \times 9.81 \times 2 \)

Now we calculate the kinetic energy for each object:

1. Table tennis ball:
\[
KE = 0.0027 \times 9.81 \times 2 \approx 0.053 \, J
\]

2. Baseball:
\[
KE = 0.147 \times 9.81 \times 2 \approx 2.89 \, J
\]

3. Small rock:
\[
KE = 0.2482 \times 9.81 \times 2 \approx 4.87 \, J
\]

4. Penny:
\[
KE = 0.0025 \times 9.81 \times 2 \approx 0.049 \, J
\]

From these calculations, the small rock has the highest kinetic energy (approximately 4.87 J) when dropped from a height of 2 meters.

Therefore, the object that will have the greatest kinetic energy is the **small rock**.