Forces

Question 1

What do objects exert onto each other?

Answer 1

Equal and opposite forces

Question 2

In what direction does the force of weight always act?

Answer 2

Downwards or towards the centre of gravity

Question 3

Do most objects have more than one force acting on them?

Answer 3

Yes

Question 4

What’s the resultant force?

Answer 4

The single force that has the same effect as all the forces acting on an object.

Question 5

What’s the unit of resultant force?

Answer 5

Newton

Question 6

If an object is accelerating there must be a ……. Acting on it?

Answer 6

Resultant

Question 7

If an object is accelerating it can be what?

Answer 7

Speeding up
Slowing down
Changing direction

Question 8

What is the resultant force of a 4N force and 3N force acting in the same direction?

Answer 8

7N

Question 9

What causes acceleration?

Answer 9

A resultant force

Question 10

Define acceleration

Answer 10

A change in velocity

Question 11

How can we find the resultant FORCE?

Answer 11

F=ma

Question 12

The greater the resultant force on an object, the greater it’s …..?

Answer 12

Acceleration

Question 13

What happens to the acceleration of an object as the resultant force on it decreases?

Answer 13

Acceleration decreases

Question 14

What is the resultant force on a car of mass 1000kg if it’s acceleration is 2m/s?

Answer 14

2000N

Question 15

What oppose the driving force of a car?

Answer 15

Friction and air resistance

Question 16

What’s the resultant force on it is zero what’s the vehicle doing?

Answer 16

Travelling at a steady speed.

Question 17

Fill in the gap:

The faster the speed of a vehicle, the bigger the __________ needed to stop it.

Answer 17

Deceleration

Question 18

What’s the stopping distance?

Answer 18

Distance it travels during the thinking distance plus the braking distance
Thinking+braking distance

Question 19

How is the thinking distance increased?

Answer 19

Driver tired, drunk or taken drugs

Question 20

The braking distance can be increase by what?

Answer 20

Poorly maintained roads
Bad weather
Condition of car
Worn brakes or tyres

Question 21

What’s the relationship between stopping distance, thinking distance and braking distance?

Answer 21

Stopping distance = thinking distance + braking distance

Question 22

If an object falls freely , what resultant force is it acting on?

Answer 22

Force of gravity

Question 23

The weight of an object is the …?

Answer 23

Force of gravity

Question 24

What’s mass and what’s weight?

Answer 24

Mass is the amount of matter in an object

Weight is the force of gravity acting on it

Question 25

The terminal velocity of an object is?

Answer 25

It's the velocity it reaches when it is falling in a fluid, the weight is then equal to the drag force on object.

Question 26

Define drag force

Answer 26

A force opposing the motion of an object due to fluid flowing past the object as it flows.

Question 27

Why does an object dropped in a fluid initially accelerate?

Answer 27

There's a resultant force acting on it.

Question 28

What eventually happens to an object falling in a fluid?

Answer 28

It will reach a terminal velocity because the resultant force becomes 0.

Question 29

What's an elastic object?

Answer 29

An object that regains it's original shape when the forces deforming it are removed.

Question 30

I we plot a graph of extension against force applied for a spring, we obtain a straight line that passes through the origin what does it tell us?

Answer 30

That extension is directly proportional to the force applied.

Question 31

A spring has a constant of 30N/m. If the extension is 0.30m, what is the force applied?

Answer 31

9 N

Question 32

How can we tell a spring has exceeded it's limit of proportionality ?

Answer 32

The line on the graph is no longer straight.

Question 33

What does Hooke's law state?

Answer 33

States that the extension is directly proportional to the force applied, provided the limit of proportionality is not exceeded.

Question 34

What to anti skid surfaces do?

Answer 34

Increase the friction between a car tyre and road surface.

Question 35

Why does making a vehicle more streamlined improve fuel economy?

Answer 35

Less engine force and less power are needed to maintain a certain speed. Therefore less fuel is needed.

Question 36

When a vehicle is travelling along a straight road at a steady speed what can you say about the engine force and the air resistance.

Answer 36

The vehicle isn't accelerating, so the resultant force on it is zero. So the engine force and air resistance are balanced.

Question 37

What are forces measured in?

Answer 37

Newtons