Energy, work and power

Question 1

Describe energy

Answer 1

It is scalar and is used to maintain the motion

Question 2

What is the unit for energy?

Answer 2

Joules J

Question 3

When is energy added?

Answer 3

If the work is done by ON the object

Question 4

When is energy reduced?

Answer 4

If the work is done BY the object

Question 5

State the equation for work done

Answer 5

Work done= Force applied * Distance moved

Question 6

What is energy?

Answer 6

The ability to do work

Question 7

State the equation for kinetic energy

Answer 7

1/2mv^2

Question 8

State the equation for gravitational potential energy

Answer 8

mgh

Question 9

Define elastic potential energy

Answer 9

The energy a material possesses when it is stretched and is put under strain

Question 10

Define thermal energy

Answer 10

The energy due to the movement of atoms and molecules in a substance

Question 11

Define chemical potential energy

Answer 11

The energy stored in the bonds of the atoms and molecules

Question 12

Define electrical energy

Answer 12

Energy due to the flow of electrons

Question 13

Define Nuclear potential energy

Answer 13

Energy stored in the nuclei of the atoms

Question 14

What is the conservation of mechanical energy?

Answer 14

If a body or system has no energy lost or added the total mechanical energy of that body or system remains constant

Question 15

Give an equation which links PE and KE in final and initial

Answer 15

(KE + PE)f = (KE + PE)i

Question 16

Give the equations that link PE and KE

Answer 16

Increase in PE= Decrease in KE

Decrease in PE= Increase in KE

Question 17

Give the equations that link PE and KE and energy lost

Answer 17

Decrease in PE= increase in KE + Energy lost

Decrease in KE= Increase in PE + Energy lost

Question 18

Give the equations that link PE and KE and energy added

Answer 18

Decrease in PE= Increase in KE- Energy added

Decrease in KE= increase in PE- Energy added

Question 19

Give the equation for power

Answer 19

Energy transferred/ time taken P=E/t

OR work done/ time

Question 20

What is the units for power?

Answer 20

Watts

Question 21

What is another unit for watts?

Answer 21

Js ^-1

Question 22

What is the principle of conserving energy?

Answer 22

Energy cannot be created nor destroyed it can only change from one form to another

Question 23

What is the equation for efficiency?

Answer 23

Useful energy output/energy input *100%

Question 24

Describe the process of generating electricity indirectly

Answer 24

The heat from the fuel boils water to make steam
It expands and pushes against the blades of a turbine
The spinning turbine then turns the generator

Question 25

State the parts of generating electricity from power stations

Answer 25

Furnace--> Boiler--> turbine--> generator

Question 26

What always happens to energy?

Answer 26

Some is ALWAYS dissipated into the surrounding/ lost to the surroundings

Question 27

List the different methods of how we can obtain energy

Answer 27

chemical energy stored in fuel – water, including the energy stored in waves, in tides, and in water behind hydroelectric dams – geothermal resources – nuclear fission – heat and light from the Sun (solar cells and panels) – wind

Question 28

Which sources are renewable?

Answer 28

Wave, tides, hydroelectric, geothermal, solar cells/panels and wind

Question 29

Which sources is the sun NOT the source of energy?

Answer 29

Nuclear, tidal and geothermal

Question 30

How does the sun release energy?

Answer 30

Nuclear fusion