A student drops a ball from a height of 60 meters. The table below shows the balls speed and height as time passes.

Question

Time | speed (m/s) | height (m)
0.0 | 0 | 60
0.5 | 7 | 53
1.0 | 10 | 43
1.5 | 15 | 28
2.0 | 20 | 8
2.5 | 0 | 0

at what point in time does the ball have the highest kinetic energy?

A. at the start (0 seconds)

B. After 0.5 seconds

C. After two seconds

D. After 2.5 seconds

Answer 1

Kinetic energy (KE) is calculated using the formula:

\[ KE = \frac{1}{2} mv^2 \]

where \( m \) is the mass of the ball and \( v \) is its speed. Since the mass of the ball does not change, we can focus on the speed \( v \) to determine when the ball has the highest kinetic energy.

From the provided table, we can see the speeds at different times:

• At 0.0 seconds: speed = 0 m/s
• At 0.5 seconds: speed = 7 m/s
• At 1.0 seconds: speed = 10 m/s
• At 1.5 seconds: speed = 15 m/s
• At 2.0 seconds: speed = 20 m/s
• At 2.5 seconds: speed = 0 m/s

The highest speed is at 2.0 seconds (20 m/s). The kinetic energy will be highest when the speed is highest, as the kinetic energy is directly proportional to the square of the speed.

Thus, the point in time when the ball has the highest kinetic energy is:

C. After 2 seconds