Review for test on Energy

An object with a mass of 20 kg is moving 5 m/s. What is it’s kinetic energy? 5 x 5 = 25 (velocity squared) 25 x 20 = 500 (mass x velocity) 500 / 2 = 250 j

3 types of potential energy: Gravitational Elastic 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 the car? 500 kg x 9.8 N = 4,940 (N) x 5 = 24,700 N

Potential energy is Not Lost…it’s converted to KE

Seven forms of energy: MRS CHEN Mechanical – Total of PE + KE Radiant – Light Sound Chemical – batteries, food Heat – Thermal Electrical Nuclear – happens in nucleus of atoms: Fission – man made; Fusion - sun

What is the difference between Heat and Temperature? Heat is. 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? Work: using a force to move an object a distance. To do work, an object must move in the direction a force is applied. Power is how quickly work is done; it is the rate, or speed, at which energy is transferred.

SI unit is in joules SI unit is in watts

Pre-AP only: If a lady ran for 3,000 seconds and her energy output 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 renewable resource and a non-renewable resource.