9 Application of Force and Transfer of Energy

Question 1

What are the two types of forces?

Answer 1

Contact force
Non-contact force

Question 2

What are contact forces?

Answer 2

Forces that acts between 2 objects in physical contact.

Question 3

What are non-contact forces?

Answer 3

Forces that acts between 2 objects not touching each other.

Question 4

Give 2 examples of contact forces.

Answer 4

friction
elastic forces

Question 5

Give 2 examples of non-contact forces.

Answer 5

gravitational force (weight)
magnetic force

Question 6

What is the SI unit of force?

Answer 6

newton (N)

Question 7

What is weight?

Answer 7

It measures the amount of gravitational force on an object.

Question 8

What is mass?

Answer 8

The amount of matter in a body.

Question 9

What is the SI unit of mass?

Answer 9

kilogram (kg)

Question 10

List down 4 differences between mass and weight.

What are they?
Their SI units
Do they change with location?
What is used to measure them?

Answer 10

1) Mass is the amount of matter in a body. Weight is the gravitational force exerted at an object.
2) SI unit of mass: kg. SI unit of weight: N.
3) Mass does not change with location. Weight changes with location.
4) Spring balance is used to measure mass. Beam balance is used to measure weight.

Question 11

What are the five effects of forces on an object?

Answer 11

1) moves a stationary object
2) stops a moving object
3) changes the direction of motion of a moving object
4) change the shape and size of an object
5) causes an object to turn

Question 12

What are the two factors that affect the amount of pressure exerted?

You can also think about how to increase pressure exerted on an object.

Answer 12

1) force exerted
2) area of contact

It must be ‘area of contact’ and not just ‘area’ or ‘surface area’.

Increased force and smaller area of contact.

Question 13

What does it mean when we say ‘energy is conserved’?

Answer 13

Energy is not created or destroyed.
It is transferred from one object to another or converted from one form to another.

Question 14

What is the SI unit for energy?

Answer 14

joule (J)

Question 15

State the 7 sources of energy.

Answer 15

1) fossil fuels
2) solar energy
3) hydroeelctric energy
4) wind energy
5) geotherma energy
6) biofuel
7) nuclear energy

Question 16

State the impact of using fossil fuel on the environment.

impact can be good or bad.

Answer 16

1) release air pollutants and greenhouse gas
2) greenhouse gas contributes to global warming and causes climate changes

Question 17

State the impact of using solar energy on the environment.

impact can be good or bad.

Answer 17

1) generate electricity without producing pollutants and greenhouse gas.
2) Toxic wastes are produced during the production and disposal of solar panels.

Question 18

State the impact of using hydroelectric energy on the environment.

impact can be good or bad.

Answer 18

1) produces very little pollutants and greenhouse gas
2) causes flooding in the area behind a dam

Question 19

State the impact of using wind energy on the environment.

impact can be good or bad.

Answer 19

1) Does not produce pollutants or greenhouse gas.
2) destroy wildlife as large plots of land needed to be cleared.
3) Birds may be killed if they collided into the blades of the wind turbines.
4) Noise pollution for the nearby communities.

Question 20

State the impact of using geothermal energy on the environment.

impact can be good or bad.

Answer 20

1) Does not produce pollutants or greenhouse gas.
2) destroy wildlife as large plots of land needed to be cleared.
3) Toxic elements underground causes harm to environment if not handled properly.

Question 21

State the impact of using biofuel on the environment.

impact can be good or bad.

Answer 21

1) release air pollutants and greenhouse gas
2) greenhouse gas contributes to global warming and causes climate changes
3) Helps to recycle and reduces wastes as biofuels can be made from food wastes and used cooking oil.
4) Helps to reduce carbon dioxide in the air as plants are grown to produce biofuels.

Question 22

State the impact of using nuclear energy on the environment.

impact can be good or bad.

Answer 22

1) Does not produce pollutants or greenhouse gas.
2) Requires less and to build than a solar or wind farm.
3) Needed a lot of effort to research for ways to dispose and store nuclear wastes safely.

Question 23

What is the energy change in a fossil fuel power plant?

Answer 23

chemical energy -> heat energy -> kinetic energy (turbine) -> electrical energy (generator)

Question 24

What is the energy change in a hydroelectric power plant?

Answer 24

gravitational potential energy (water behind the dam) -> kinetic energy (water) -> kinetic energy (turbine) -> electrical energy (generator)

Question 25

What is the energy change in a wind power plant?

Answer 25

kinetic energy (wind) -> kinetic energy (turbine) -> electrical energy (generator)

Question 26

What is the energy change in a geothermal power plant?

Answer 26

heat energy (earth’s core) -> kinetic energy (steam) -> kinetic energy (turbine) -> electrical energy (generator)

Question 27

What is the energy change in a nuclear power plant?

Answer 27

nuclear energy (atoms) -> heat energy -> kinetic energy (turbine) -> electrical energy (generator)

Question 28

What is the energy change in a solar power plant?

Answer 28

light energy (sun)-> electrical energy (solar cell)