Question

1. Which has more kinetic energy, a 40 kg cheetah running at 25 m/s or a 4,000 kg elephant moving at 2 m/s? How much more energy does it have?
2. At what speed would the animal with less KE have to travel to have the same kinetic energy as the animal with more KE?

3. Discuss the kinetic and potential energy of the ball on the end of a pendulum as it swings from point A to point B. Explain the kinetic energy and potential energy of the ball at each point and what happens to energy as the ball moves from point A to point B. In your discussion, answer the following questions: When is the kinetic energy of the ball zero and when is it at its highest? When is its potential energy at its lowest and at its highest? What happens to the kinetic energy and potential energy between point A and point B?

Answer 1

Answer:

1. The elephant has more kinetic energy at this speed and mass. It has 4,500 J more KE.

2. The elephant would have to go at a speed of 2.5 m/s to reach the same KE as the cheetah.

Explanation:

You would use the formula KE=1/2mv^2.

This formula would be filled in and completed twice, once for the elephant and once for the cheetah.

Cheetah:

KE = 1/2 (40) (25) ^2

KE = 12,500 J

Elephant:

KE = 1/2 (4,000) (2) ^2

KE = 8,000 J

This shows that the cheetah has more KE.

Then you would subtract the elephants amount of J from the cheetahs to find the difference.

Difference = 12,500 J - 8,000 J

Difference = 4,500 J

I hoped this helped with the first part :)

For the second part:

To find the speed the elephant would have to run you would fill in and complete the equation once more with different distance results.

KE = 1/2 (4,000) (2.5) ^2

KE= 12,500 J