chapter 9: applications of forces, transfer of energy

Question 1

What is the result of climate change?

Answer 1

Increase in the temperature of sea surfaces.

Question 2

What causes tropical cyclones?

Answer 2

Increase in temperature of sea surfaces, which results in longer and more intense storms. (is tropical cyclones)

Question 3

What are tropical cyclones accompanied with, and what does it cause?

Answer 3

Accompanied with heavy rain and strong winds. The heavy rainfall causes landslides.

Question 4

How do earthquakes occur?

Answer 4

Surface of earth made up of pieces of solid rock called plates, slide over/ against each other, force exerted results in great energy released, causing an earthquake.

Question 5

How do volcanic erruptions occur?

Answer 5

Deep in earth, rock melts = magma. Earth moves violently when magma is pushed out of the earth with great force, causing a volcanic erruption. Energy stored within earth is released as heat, light and kinetic energy of magma.

Question 6

How do tsunamis occur?

Answer 6

Vigorous movement of ocean floor due to earthquakes/volcanic erruption, which displaces ocean water.

Question 7

Why do tsunamis move fast?

Answer 7

Tsunami waves rise to 40m, which greatly increases potential energy of waves. Potential energy is converted to kinetic energy which enables to waves to move at fast paces towards the shore.

Question 8

What do tsunamis cause?

Answer 8

Erosion of coastlines, loss of lives, destruction of the environment and buildings.

Question 9

What are contact forces?

Answer 9

Forces acting between two objects by physical contact.

Question 10

What is friction?

Answer 10

it is the force that opposes motion between two objects.

Question 11

What is elastic force?

Answer 11

Force acting on a stretched/compressed elastic material to return to its original size. The elastic material which is compressed/stretched resists change in shape by exerting force in the opposite directions.

Question 12

What are non contact forces?

Answer 12

Forces acting between two objects without physical contact.

Question 13

What is gravitational forceS?

Answer 13

Force that attracts two objects towards each other.

Question 14

What is weight?

Answer 14

When exerts gravitational force on an object and pulls it to the centre, the object has weight.

Question 15

What is magnetic force?

Answer 15

Force exerted between magnet(s) and another magnetic material.

Question 16

What are the two poles of a magnet?

Answer 16

North and south.

Question 17

What happens when two unlike poles of a magnet face each other?

Answer 17

They attract.

Question 18

What happens when two like poles of a magnet face each other?

Answer 18

They repel.

Question 19

What is weight? What is its SI unit?

Answer 19

Weight is the measure of gravitational potential energy acting on an object. SI unit is Newton (N), same as SI unit of force as it is a force.

Question 20

What is mass? What is its SI unit?

Answer 20

Mass is the amount of matter inside an object. SI unit is kilograms (kg)

Question 21

How do we measure forces? How does it work?

Answer 21

Use a spring balance. Spring stretches when force is applied, thus allowing the weight to be read.

Question 22

Uses of spring balances?

Answer 22

Measure amount of force due to a pull.

Question 23

What can the transfer of energy between objects cause?

Answer 23

1. Movement of a stationary object
   2.Change of speed in an object
2. Change in direction in which an object moves
3. Stop a moving object

Question 24

What is the effect of forces on an object?

Answer 24

1. Turning effect
2. Changes of size/shape of an object

Question 25

What is the turning effect? What can it do?

Answer 25

When force is applied on an object, it could cause a turning effect about a fixed point called a pivot. Can help carry out on action with minimal force.

Question 26

Why does an object shape change when a force is applied?

Answer 26

Due to transfer of energy

Question 27

What is pressure? What defines the amount of pressure?

Answer 27

An effect of force acting on an object. The surface contact defines the amount of pressure. small contact = up pressure

Question 28

How to calculate pressure? What is its unit?

Answer 28

Force (N) over Area (m^2)
Unit is force per unit area (N/m^2) / Pascal (Pa)

Question 29

What happens when you swim deeper underwater?

Answer 29

Higher pressure on body.

Question 30

Why is the base of the dam thicker than the top?

Answer 30

The water pressure is higher at the base, so the thick wall can withstand pressure.

Question 31

What happens when we are above sea level?

Answer 31

less atmospheric pressure as fewer air particles push down on us.

Question 32

How does atmospheric pressure tropical cyclones, and climate change relate?

Answer 32

Sun warms water on ocean surface, evaporates, rises, and thus lower air pressure near the surface of ocean. Air from surrounding area of higher air pressure flows into lower air pressure.

Question 33

How does a drinking straw work?

Answer 33

Air is sucked out of straw, lower air pressure. Outside has higher atmosphere pressure, pushing liquid up.

Question 33

How does a drinking straw work?

Answer 33

Air is sucked out of straw, lower air pressure. Outside has higher atmosphere pressure, pushing liquid up.

Question 34

How does a suction cup work?

Answer 34

Air is pushed out, air pressure between suction cup and surface decreases, can stick

Question 35

What is work?

Answer 35

Work happens when energy is transferred. Done through the application of force.

Question 36

What is the SI unit for work?

Answer 36

joule (J)

Question 37

What conditions need to be satisfied for work to be considered done?

Answer 37

1. force is applied on object
2. Object moves
3. Object moves in same direction the force is applied.
4. When work is done, energy is transferred.