Energy, Work & Power

Question 1

Energy is measured in…

Answer 1

Joules (J)

Question 2

Can energy be created or destroyed?

Answer 2

Neither

Question 3

The formula for kinetic energy is…

Answer 3

Ek = 1/2mv^2

Question 4

The formula for work is…

Answer 4

W = Fd

Question 5

W = Fd is the formula for…

Answer 5

Work

Question 6

What is Chemical Potential Energy?

Answer 6

Energy that is stored in the bonds between atoms. Found is substances such as petrol and food.

Question 7

What is Electrical Energy?

Answer 7

The movement of electrically charged particles. Found in wires, generators and lightning.

Question 8

What is Gravitational Potential Energy?

Answer 8

Energy stored in objects due to their height above the ground.

Question 9

What is Heat Energy?

Answer 9

Caused by the movement of particles. Found inside all heated/hot objects.

Question 10

What is Light Energy?

Answer 10

The energy of electromagnetic waves. Found in microwaves, X-rays and visible light.

Question 11

What is Sound Energy?

Answer 11

Energy produced by vibrating objects. Examples include speech, ultrasound and music.

Question 12

What is Kinetic Energy?

Answer 12

Energy of an object due to its motion. Examples include moving cars, running and swimming.

Question 13

What is Elastic Potential Energy?

Answer 13

Energy stored in stretched or squashed objects. Examples include springs and rubber bands.

Question 14

What is the formula for Gravitational Potential Energy?

Answer 14

Change in Gravitational Potential Energy (Ep) = mass (m) x gravity (g) x change in height (h) or Ep=mgh

Question 15

What is power?

Answer 15

The rate at which work is done.

Question 16

What is the formula for Power?

Answer 16

Power (p) = Work (W) divided by Time (t) or P=W/t

Question 17

An object has more kinetic energy if…

Answer 17

its mass or speed is greater

Question 18

When is work done on an object?

Answer 18

Work is done on an object when a force causes the object to move in the direction of the force. The amount of work done on an object depends on the force applied to that object and the distance the object travels.

Question 19

A book that weighs 4N and is lifted onto a shelf 3m higher than its original position, calculate the work done

Answer 19

w= F x d
= 4N x 3m
=12 j

Question 20

What does the law of conservation of energy state?

Answer 20

Energy can’t be created or destroyed, it can only be transformed or transferred from one form to another

Question 21

Why will a ball never rebound to the same height it was dropped from?

Answer 21

The rebound energy is smaller than the the initial energy because not all of the kinetic energy is conserved, it is transferred into other types of energy such as heat and sound.