Interatcions: Forces

Question 1

What is a force?

Answer 1

A force is a push or a pull

Question 2

Can a force be seen?

Answer 2

No, a force cannot be seen.

However, its effects can be felt or seen.

Question 3

What can a force do?

(Hint: There are 5 things a force can do)

Answer 3

A force can:
• Move a stationary object
• Stop a moving object
• Change the shape of an object, bend or break it
• Change the direction of a moving object
• Change the speed of a moving object

Question 4

What causes objects to have weight?

Answer 4

Objects have weight because of the gravitational force between them and the Earth

Question 5

What are the different types of forces?

(Hint: there are 4 types)

Answer 5

The different types of forces include:
* Magnetic force
* Gravitational force
* Elastic spring force
* Frictional force

Question 6

Fill in the blank: A force is a _______ or a pull.

Answer 6

Push

Question 7

True or False: The effects of a force can only be seen, not felt.

Answer 7

False. The effects of a force may be seen, or felt, or both.

Question 8

What indicates that all forces acting on an object are balanced?

Answer 8

The object does not move.

Question 9

What happens to a wooden block when two people apply equal forces?

(See picture)

What if the forces are unequal?

two people pushing a block

Answer 9

It remains stationary with equal (balanced) forces, but if the forces are unequal the block would move.

Question 10

For a force to be exerted, what is needed?

Answer 10

Energy is needed for a force to be exerted.

Question 11

What is magnetic force?

Answer 11

The force exerted by a magnet.

Question 12

What are the two poles of a magnet called?

Answer 12

North-pole and South-pole.

Question 13

What is magnetic force of attraction?

Answer 13

The pulling force exerted when two unlike poles face each other, OR when a magnetic material is attracted to a magnet.

Question 14

Gives examples materials that are considered magnetic?

Answer 14

Certain metals:

• Iron
• Steel
• Cobalt
• Nickel

Question 15

What do unlike poles of magnets do?

Answer 15

Exert a pulling force towards each other.

Question 16

What is magnetic force of repulsion?

Answer 16

The pushing force exerted when two like poles face each other.

Question 17

What do like poles of magnets do?

Answer 17

Exert a pushing force towards each other.

Question 18

Where is the strongest point of a magnet?

Answer 18

Magnetic force is strongest at the poles of a magnet.

Question 19

Can magnetic force pass through magnetic materials?

What about non-magnetic materials?

Answer 19

Magnetic force cannot pass through magnetic materials (like iron, cobalt, nickel, and steel), but it can pass through non-magnetic materials.

Question 20

Can magnetic force act from a distance?

Answer 20

Yes, magnetic force can act from a distance.

Question 21

What produces friction?

Answer 21

Friction is produced when two objects rub against each other.

Question 22

In which direction does friction act?

Answer 22

Friction acts in the opposite direction of motion.

Question 23

What effect does friction have on a moving object?

Answer 23

Friction can cause a moving object to slow down, and come to a stop eventually.

Question 24

What does friction produce?

Answer 24

Friction produces heat.

Question 25

What causes wear and tear on a car’s tyres?

Answer 25

The **friction between the tyre and the ground** causes the tread on the tyre to wear off.

Question 26

How does friction waste energy?

Answer 26

Friction wastes energy as (extra) **energy is needed to overcome friction** (in machinery, or even in our daily chores).

Question 27

Give some examples of *useful* aspects of friction?

Answer 27

Friction allows us to: • grip things without dropping them (like a hammer) • drive a vehicle without skidding (like a bike) • walk without slipping (like, um… walking) • and stop moving objects (like a ball rolling on a carpet)

Question 28

What causes a boy to come to a stop on a slide?

Answer 28

The **friction between the boy and the surface of the slide** causes him to come to a stop.

Question 29

What does the amount of friction between two surfaces depend on?

Answer 29

The **roughness or smoothness** of the two surfaces.

Question 30

How does surface roughness affect friction?

Answer 30

The **rougher** the two surfaces, the **greater** the friction between them.

Question 31

How can friction be reduced?

Answer 31

By using **lubricants, rollers, or wheels**.

Question 32

What is air resistance?

Answer 32

The **force of the air** pushing against a *moving* object.

Question 33

What is water resistance?

Answer 33

The **force of the water** pushing **against a moving object** as it moves *through water*.

Question 34

Can friction act from a distance?

Answer 34

No, friction **cannot** act from a distance.

Question 35

What is gravitational force?

Answer 35

The **pulling force** exerted on objects *by the Earth*.

Question 36

What is weight?

Answer 36

The **measure** of *gravitational force on an object*.

Question 37

What happens to weight in places with no gravity?

Answer 37

We are **weightless** in places where there is no gravity.

Question 38

How do **weight** and *mass* differ?

Answer 38

• MASS is the **amount of substance** in an object (*does not change with position*) • WEIGHT, as a **measure of gravitational force**, *changes with the position* of an object (relative to the source of gravity).

Question 39

What prevents objects from floating into space (from the Earth)?

Answer 39

Gravity (between the Earth and the objects).

Question 40

What is elastic spring force?

Answer 40

The force exerted by a **compressed** OR an *extended* spring.

Question 41

What does a compressed spring do?

Answer 41

A compressed string exerts a **pushing** force. (See photo)

Question 42

What does a stretched spring do?

Answer 42

A stretched spring exerts a **pulling** force. (See photo)

Question 43

How does the weight of an object affect spring force?

Answer 43

The **heavier the object** compressing or stretching the spring, **the greater the compression or extension**, and the **greater the force** exerted.

Question 44

What is the **elastic limit** of a spring?

Answer 44

Elastic limit is the point beyond which a spring **cannot be compressed or extended further**.

Question 45

Can elastic spring force act from a distance?

Answer 45

No, elastic spring force **cannot act from a distance**.

Question 46

Can gravity act from a distance?

Answer 46

Yes, gravity can (and does) act from a distance.