Review for test on Energy

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An object with a mass of 20 kg is moving5 m/s. What is its kinetic energy?

5 x 5 = 25 (velocity squared)25 x 20 = 500 (mass x velocity)500 / 2 = 250 j

3 types of potential energy:

1. Gravitational2. Elastic3. Chemical

All energy is measured in Joules

GPE = weight (N) x height (m)Weight = mass (kg) x gravity (9.8 N)GPE can also be stated as mgh

A lift raises a 500 kg car 5 m off the ground.What is the potential energy given to thecar?

500 kg x 9.8 N = 4,940 (N) x 5 = 24,700 j

Potential energy is NotLost…it’s converted to KE

Seven forms of energy:

MRS CHENMechanical – Sum of PE + KERadiant – LightSoundChemical – batteries, foodHeat – Thermal ElectricalNuclear – happens in nucleus of atoms:

Fission – man made; Fusion - sun

What is the difference between Heat andTemperature?

Heat is the total energy of molecular motion in a substance while temperature is a measure of the average energy of molecular motion in a substance.

Floor heater

What is work?What is power?

Power is how quickly work is done; it is the rate, or speed, at which energy is transferred.

Work: using a force to move an object a distance. To do work, an object must move in the direction a force is applied.

SI unit is in joules

SI unit is in watts

Pre-AP only:

A lady ran for 3,000 seconds and her energyoutput is 270,000 joules. What was her average power?

Power = work (J) / time (s)

270,000 / 3,000 = 90 watts

Initial PE changes to Electrical energy

Know the difference between a renewableresource and a non-renewable resource.