Physical Science

Ch 15-1 Energy and its’ Forms

Power Standard P4.3A, B, C

Quick Quiz Questions

1. What is the energy of motion called?
1. elastic, potential, kinetic
2. GPE is related to gravity, height, reference level and ____ .
1. position, size, mass
3. Give an example of an object that has elastic potential energy.
4. Which energy form increases when an object gets warmer?
1. kinetic, mechanical, thermal

ENERGY and WORK

• Energy is the ability to do work
• Work transfers energy
• Energy is measured in Joules (j)

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There are 2 types of ENERGY

1. Kinetic
2. Potential

Kinetic Energy

• The energy of motion
• Kinetic energy depends on its mass and speed (velocity)
• Kinetic Energy = 1/2mv²

Joule is the unit for energy

A .10kg bird is flying at a constant speed of 8.0 m/s. What is the bird’s kinetic energy?�

• m = .10kg
• v = 8.0 m/s
• KE=½(.10kg)(8.0 m/s)² = 3.2J
• The kinetic energy of the bird is 3.2J

• This is asking us to find the kinetic energy.
• Formula is 1/2mv²

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1. What is the problem asking us to find?
2. What formula/equation do we need to use?
3. What is the data in the problem that we need?
4. Put the data into the formula dnd calculate.
1. Remember to include a unit.

Potential Energy

• Stored energy due to position or shape
• Two types
• Gravitational Potential depends on mass, height and gravity. Height is relative to a point
• GPE = mgh g (on earth) is 9.8 m/s²
• Elastic Potential energy of an object that is stretched or compressed.

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A diver at the top of a 10 m board has a mass of 50 kg. What is her potential energy relative to the water below?

• The problem asks for the gravitational potential energy
• GPE = mgh
• m= 50kg g= 9.8m/s² h= 10m
• GPE=(50kg)(9.8m/s)(10m)=4900J
• The diver has a potential energy of 4900J

1. What is the problem asking us to find?
2. What formula/equation do we need to use?
3. What is the data in the problem that we need?
4. Put the data into the formula dnd calculate.
1. Remember to include a unit.

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Forms of energy

• Mechanical – energy associated with position and motion of everyday objects
• Thermal –(heat) Total kinetic and potential energy of all particles of an object
• Chemical – is the energy stored in the chemical bonds in compounds

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Forms of energy

• Electrical – energy associated with electrical charges
• Electromagnetic – Energy that travels through space in waves (visible light and x-rays are examples)
• Nuclear – energy stored in atomic nuclei.

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Quiz Answers

1. What is the energy of motion called?
1. kinetic
2. GPE is related to gravity, height, reference level and ____ .
1. mass
3. Give an example of an object that has elastic potential energy.
4. Which energy form increases when an object gets warmer?

- thermal

• Solar cells convert ___ energy into electricity.

- Electromagnetic

Summary

• Kinetic energy is the energy of motion.
• Potential energy is the energy of position.
• There are 6 basic forms of energy mechanical, thermal, chemical, electrical, electromagnetic, and nuclear.
• For nuclear energy, atoms are split and the heat generated is created.