# Kinetic and potential energy

### Energy - Exercise 07

A tennis ball is dropped from a height of 2 m. At what speed does it hit the ground?

### Energy - Exercise 08

A ball has a mass of 0'5 kg. Dropped from a cliff top, the ball hits the sea below at a speed of 10 m/s.

1. What is the kinetic energy of the ball as it is about to hit the sea?
2. What was the ball's gravitational potential energ before it was dropped?
3. From what height was the ball dropped?

### Energy - Exercise 09

If we drop to the floor a stone which has a mass of 4 kg from a height of 4 m,

1. What is its kinetic energy when it has fallen half-way to the ground?
2. What is its speed when it reaches the floor?

### Energy - Exercise 10

Consider again the example of dropping a ball whose mass is a 0'2 kg. Calculate the gravitational energy lost by the ball upon falling 3 m.

### Energy - Exercise 11

Use conservation of energy to predict the speed of a dropped object that has fallen a distance of half a meter.

### Energy - Exercise 12

Imagine dropping a mass of 1.000 kg from a plane when it is at a height of 800 m. Find out its kinetic and potential energy:

1. At the exact moment of dropping it.
2. When the object has fallen 430 m.

### Energy - Exercise 13

Imagine dropping a stone whose mass is 10 kg. from a height of 500 m.

1. Calculate its energy at the highest point. Which type is it?
2. Calculate its kinetic energy when hits the floor.

### Energy - Exercise 14

Imagine dropping a stone whose mass is 5 kg from a height of 200 m.

1. Calculate its potential energy at the highest point.
2. Calculate its kinetic energy when it hits the floor.

### Energy - Exercise 15

Imagine dropping a mass from a plane flying at a speed of 900 km/h when it is at height of 3 km. Find out its speed when it hits the floor.

### Energy - Exercise 16

Imagine dropping a ball of 500 g from window situated 30 m above the floor. Find out:

1. Its potential energy when it is dropped.
2. Its kinetic energy when it hits the floor.
3. Its speed when it hits the floor