Table of Contents 8.2 What Is Energy? Energy and Motion
Vocabulary 8.1 Energy: The ability to do work or cause change. Joule: S.I. unit that measures energy Kinetic Energy: Energy that an object has due to its motion. Potential Energy: The energy an object has because of its position; also the internal stored energy of an object, such as energy stored in chemical bonds. Gravitational Potential Energy: Potential energy that depends on the height of an object. Elastic Potential Energy: The energy of stretched or compressed objects.
How are Energy, Work, and Power Related? Pg. 290 What is ENERGY? Energy is the ability to do work or cause change. Rd. pgs. 290, 291 When you do work on an object, some of your energy is transferred to that object. You can think of work as the transfer of energy. Both work and energy are measured in joules. S.I. Unit for WORK & ENERGY= JOULES
Formula to Solve for Power pg. 291 You may recall that power is the rate(speed) at which work is done. Since the transfer of energy is work, then the rate at which energy s transferred, or the amount of energy transferred in a unit of time. Power = Energy Transferred Time
What Are the Two Types of Energy? Pg. 292 Kinetic Energy The 2 Basic types of energy are: Potential Energy Whether energy is kinetic or potential depends on: The motion, the position, and the shape of the object. The energy an object has due to its motion is ________energy. Kinetic energy of an object depends on 2 factors: its speed (how fast is moving) its mass. r. p 3 &4 The faster an object moves, the more kinetic energy it has. Kinetic energy also increases as mass increases.
Kinetic Energy The kinetic energy of an object depends on its speed and mass. 1.List the vehicles in order of increasing kinetic energy. ___________________________ ___________________________ __________________ 2. Describe another example of two objects that have different kinetic energies. Explain why their kinetic energies are different. ___________________________ ___________________________ ___________________________ What Is Energy? Pg. 292
Formula for Solving for Kinetic Energy 2 Kinetic Energy= 1 x Mass x Speed 2 Changing the speed of an object will have a greater effect on its kinetic energy than changing its mass by the same factor. This is because speed is squared in the kinetic energy equation.
Potential Energy pg. 294 Potential energy is energy that results from the position or shape of an object. This type of energy has the potential to do work. Gravitational potential energy is the potential energy related to an object’s height. Force is measured in S.I units= NEWTONS (N) The gravitational potential energy of an object is equal to the work done to lift it to that height. You can calculate an object’s gravitational potential energy using this equation. Gravitational potential energy = Weight × Height
What is the SI unit for each quantity? What Is Energy? Pg. 294
Figure 3 Gravitational Potential Energy The rock climbers have gravitational potential energy, which is potential energy related to an object's height. 1.Circle the rock climber with the greatest potential energy. Calculate this potential energy. The height to be used is at the rock climber’s lowest foot. ______________________ 2. Where would the rock climbers at the top have to be to have half as much potential energy?___________________ __________________________ __________________________ __________________________
Elastic Potential Energy pg. 295 Figure 4 Elastic potential energy is the energy associated with objects that can be compressed or stretched. The energy stored in a trampoline is elastic potential energy. Art in Motion
Elastic Potential Energy The energy stored in a stretched object, such as the trampoline, is elastic potential energy. Rank the amount of elastic potential energy of the trampoline from greatest to least. (1=greatest) write your answers in the circle What Is Energy?