Conservation of Energy

Front

What is the definition of gravitational potential energy?

Back

Gravitational potential energy is the energy an object possesses due to its position in a gravitational field, calculated as PE = mgh, where m is mass, g is the acceleration due to gravity, and h is height above a reference point.

Front

How do you calculate gravitational potential energy?

Back

Gravitational potential energy (PE) is calculated using the formula: PE = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (approximately 10 m/s² on Earth), and h is the height in meters.

Front

What is the gravitational potential energy of a 50 kg dog at a height of 2 meters?

Back

PE = mgh = 50 kg * 10 m/s² * 2 m = 1000 J.

Front

If an object is dropped from a height, what happens to its gravitational potential energy?

Back

As the object falls, its gravitational potential energy decreases while its kinetic energy increases, conserving the total mechanical energy.

Front

What is the significance of the reference point in gravitational potential energy calculations?

Back

The reference point is the height from which potential energy is measured; it can affect the calculated value of gravitational potential energy.

Front

How does the height affect gravitational potential energy?

Back

Gravitational potential energy increases with height; doubling the height will double the potential energy, assuming mass and gravity remain constant.

Front

What is the gravitational potential energy of a 100 kg man on the second floor, 3.5 meters above the ground?

Back

PE = mgh = 100 kg * 10 m/s² * 3.5 m = 3500 J.

Front

What is the gravitational potential energy of a 10 kg box on a shelf 1.5 meters high relative to a shelf 2.0 meters high?

Back

The height difference is 0.5 m, so PE = mgh = 10 kg * 10 m/s² * 0.5 m = 50 J.

Front

What is the formula to find the height from which an object was dropped if its speed upon hitting the ground is known?

Back

Use the formula: h = v² / (2g), where v is the final velocity and g is the acceleration due to gravity.

Front

If a cement block hits the ground at 30 m/s, what was the height from which it was dropped?

Back

Using h = v² / (2g), h = (30 m/s)² / (2 * 10 m/s²) = 45 m.