energy and work done

Question 1

what is energy

Answer 1

ability to do work

Question 2

why do living things need energy?

Answer 2

to keep them alive and active

Question 3

do non-living things need energy to do work?

Answer 3

yes

Question 4

what is work?

Answer 4

the use of a force to move an object in the direction of the force

Question 5

conditions for work to be done

Answer 5

• there is force acting on an object
• the object moves
• the object moves in the direction of the force

Question 6

is work done if any of these are missing?

Answer 6

no

Question 7

what does the amount of work depend on?

Answer 7

• the size of the force applied

- the distance moved by the object in the direction of the force

Question 8

what is the SI unit of work?

Answer 8

Joule ( J )

Question 9

what is one joule?

Answer 9

one joule is the work done when a force of one Newton moves an object by one meter in the direction of the force

Question 10

larger unit of work

Answer 10

kilojoule (kJ)

Question 11

1kJ = ?

Answer 11

1000J

Question 12

equation for work done

Answer 12

w = f * d

Question 13

no work answer technique

Answer 13

no work is done on ( object )
a force of ( ) is exerted on the ( object ), which moves over a distance.
however, the distance moved by the ( object ) is not in the same direction as the force

Question 14

work done answer technique

Answer 14

there is work done on ( object ) because a force of ( force ) is applied to move the ( object ) over a distance of ( distance ). The ( object ) moves in the same direction in which the force was exerted.

Question 15

how are energy and work related?

Answer 15

when work is done, energy is transferred from one thing to another.
work done = energy transferred
when one joule of work is done, one joule of energy is transferred.

Question 16

different forms of energy ( 6 energy )

Answer 16

kinetic energy
potential energy
sound energy
electrical energy
thermal energy
light energy

Question 17

factors of kinetic energy

Answer 17

• moving objects have kinetic energy

- kinetic energy can be used to do work

Question 18

factors of potential energy

Answer 18

• energy that is stored
• can be converted to kinetic energy and vice versa
• exists in many forms
  »elastic potential energy in an archer’s bow
  » an object has gravitational potential energy when it is raised to a certain height above the ground

Question 19

how to find gravitational potential energy

Answer 19

mass of body ( kg ) * gravitational field * height ( m )

Question 20

law of conservation of energy

Answer 20

• energy cannot be created or destroyed
• energy can only change from one form to another
• total amount of energy and after the change is exactly

Question 21

sources of energy

Answer 21

• wood, water and wind
• main sources of energy now : coal, oil and natural ( fossil fuels )
• fossil fuels were formed from the remains of dead plants and animals that lived about 300 million years ago and are buried deep underground