GRAVITATIONAL POTENTIAL ENERGY

MR. T

VIDEO

VIDEO

POTENTIAL ENERGY An object can store energy as the result of its position.

The energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.

KINETIC ENERGY

Kinetic energy is the energy of motion.

Potential energy is stored energy. (no motion).

TODAY WE ARE TALKING ABOUT .. Gravitational potential energy!!!!

Gravitational potential energy is the energy stored in an object as the result of its vertical position or height.

The energy is stored as the result of the gravitational attraction of the Earth for the object

GRAVITATIONAL POTENTIAL ENERGY There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy.

There is also a direct relation between gravitational potential energy and the height of an object. The higher the height the more potential energy.

GRAVITATIONAL POTENTIAL ENERGY

LETS LOOK AT THE EQUATION PEgrav = m • g • h

In the above equation, m represents the mass of the object, h represents the height of the object and g represents the gravitational field strength (9.8 N/kg on Earth) - sometimes referred to as the acceleration of gravity.

IMPORTANT

In this class you will not be asked to do calculations on a test or quiz.

BUT you should be able to tell me if the Gravitational potential energy would decrease or increase if I change variables in the equation.

EXAMPLE

A rock that has a mass of 20kg is on a cliff that is 20m high. How would the Gravitational potential energy change if it was on a cliff that was 30m high?

ANSWER

The GPE would increase because h in the equation

PEgrav = m • g • h is increasing.

EXAMPLE

A rock that has a mass of 20kg is on a cliff that is 20m high. How would the Gravitational potential energy change if it was on a mass of the rock only 15kg?

ANSWER

The GPE would decrease because the m in the equation

PEgrav = m • g • h is decreasing.

GPE IN A PENDULUM

PENDULUM

At which point(s) does the pendulum have the most potential energy?

At which point(s) does the pendulum have the most kinetic energy?

Name two point where the pendulum is increasing in kinetic energy.

PENDULUM

At point “D” the pendulum is _______________ kinetic energy because it is __________________ its speed. Meanwhile it is _______________ potential energy because it is __________________ its height.