8B Forces

Question 1

State two examples of contact forces.

Answer 1

Friction, air resistance, tension, normal contact force, and Upthrust

Question 2

State two examples of non-contact forces.

Answer 2

Magnetism, gravity, and electrostatic force.

Question 3

What is resultant force?

Answer 3

The overall force acting on an object.

Question 4

What do the arrows on a free body diagram show us?

Answer 4

The direction of the forces acting on an object.

Question 5

What are balanced forces?

Answer 5

Forces equal in size, acting in opposite directions.

Question 6

Define equilibrium.

Answer 6

The forces acting on an object are balanced.

Question 7

Describe the effect of zero resultant force on a stationary object.

Answer 7

It remains stationary

Question 8

Describe the effect of zero resultant force on a moving object.

Answer 8

It remains at a constant speed.

Question 9

Define what a frictional force is.

Answer 9

A force that acts in the opposite direction to the movement of an object.

Question 10

What is drag?

Answer 10

A frictional force where one of the surfaces is a fluid (a liquid or gas).

Question 11

Give an example of useful frictional force.

Answer 11

Friction between tyres and breaks.

Question 12

Give an example of unhelpful frictional force.

Answer 12

Air resistance on moving objects

Question 13

What is streamlining?

Answer 13

Changing the shape of an object to reduce drag.

Question 14

Describe how penguins are streamlined to swim through the water.

Answer 14

The penguin has a specific shape that means it moves through the water easily.

Question 15

Describe how cyclists reduce drag during races.

Answer 15

They have streamlined helmets and crouch low to reduce drag.

Question 16

Why is it useful for racing cars to be streamlined?

Answer 16

So that they can move faster.

Question 17

Define deformation.

Answer 17

When something changes shape.

Question 18

What is the difference between elastic and inelastic deformation?

Answer 18

Elastic- an object returns to its original shape after a force is removed, inelastic does not.

Question 19

How does compression affect an object?

Answer 19

Squashes it.

Question 20

How does tension affect an object?

Answer 20

Stretches it.

Question 21

Describe how force and extension are directly proportional for springs.

Answer 21

When an increasing force is applied, the extension increases at the same rate.

Question 22

What does spring constant tell us about an object?

Answer 22

How much force it would take a spring to stretch a certain distance.

Question 23

Give one use for elastic materials.

Answer 23

Sports clothing

Question 24

Give one use for brittle materials.

Answer 24

Building materials.

Question 25

What is an elastic material?

Answer 25

When an object is deformed by returns to its original shape when the force is removed.

Question 26

What equipment is required when investigating the elasticity of a material?

Answer 26

Clamp and retort stand, ruler, weights, spring and weight holder.

Question 27

What happens if an object is stretched beyond its elastic limit?

Answer 27

It does not return to its original shape.

Question 28

State Hooke’s Law.

Answer 28

The force applied to a spring is directly proportional to its extension.

Question 29

What graph can be plotted when investigating the elasticity of a material?

Answer 29

Force against extension.

Question 30

How can spring extension be calculated?

Answer 30

Extended spring length – initial spring length.

Question 31

State the equation which links spring constant, force and extension.

Answer 31

Spring constant = Force ÷ Extension

Question 32

What are the units of measurement for spring constant, force and extension?

Answer 32

Spring constant (N/m), Force (N) and Extension(m)

Question 33

What is the independent variable for testing Hooke's Law?

Answer 33

Number of masses added.

Question 34

How will you convert the length of the spring from mm into metres?

Answer 34

Divide by 1000

Question 35

How do you calculate extension?

Answer 35

Subtract the initial length from the new length when weights are added.

Question 36

What force is equal to a 100g mass?

Answer 36

1N

Question 37

What is the initial force acting on the spring?

Answer 37

0N

Question 38

How will you calculate the spring extension of each material?

Answer 38

Spring extension = force ÷ extension.

Question 39

What is a line of best fit?

Answer 39

A line that goes through most points, but is not a dot to dot.

Question 40

How do you draw a line of best fit?

Answer 40

Draw a line that goes through most of the points.

Question 41

What is the limit of proportionality?

Answer 41

The point after which the extension is not directly proportional to force.

Question 42

What is pressure?

Answer 42

A force exerted over a certain area.

Question 43

What are the units of measurement for pressure?

Answer 43

Pascals (Pa) or N/m2

Question 44

State the two factors which determine pressure exerted by an object.

Answer 44

Force/ weight and area

Question 45

Give an example of a situation where pressure is high.

Answer 45

Treading on a single nail.

Question 46

Give an example of a situation where pressure is low.

Answer 46

Lying on a bed of nails.

Question 47

Why do high heels and flat shoes exert different pressures?

Answer 47

They have a smaller area touching the floor.

Question 48

State the equation which links pressure, force and area.

Answer 48

Pressure = Force ÷ Area

Question 49

When calculating pressure, what could be used instead of force?

Answer 49

Weight

Question 50

What causes liquid and gas pressure?

Answer 50

Particles colliding with a surface.

Question 51

What does liquid or gas pressure depend on?

Answer 51

Depth and altitude.

Question 52

Why don’t we normally notice pressure on our bodies?

Answer 52

Pressure inside and outside our bodies is equal.

Question 53

State how pressure changes with depth in a liquid.

Answer 53

Pressure increases with depth in a liquid.

Question 54

Why does pressure change as you go deeper in a liquid?

Answer 54

The number of liquid particles above something increases and the force of gravity pulling these particles down also increases.

Question 55

State how pressure changes with altitude in a gas.

Answer 55

Pressure decreases with altitude.

Question 56

Why are there fewer air particles as you increase in altitude?

Answer 56

Gravity is weaker higher up.

Question 57

How do airplanes compensate for a drop in pressure outside?

Answer 57

As you increase your altitude, the pressure in the cabin decreases slightly.

Question 58

Define density.

Answer 58

The mass of a material in a particular volume, measured in kg/m3.

Question 59

What determines whether an object floats or sinks in water?

Answer 59

Its density in comparison to water.

Question 60

What is buoyancy?

Answer 60

An upward force on an object in a liquid.

Question 61

What happens when objects are placed in water?

Answer 61

Weight pulls it down and Upthrust pushes it upwards.

Question 62

What is the upward force of water acting on an object?

Answer 62

Upthrust

Question 63

How can we find the upward force of water acting on an object?

Answer 63

Find the volume of water displaced by the object

Question 64

How are large ships able to float, despite having a large mass?

Answer 64

They have a greater weight, so a greater force of Upthrust acts on them.

Question 65

Who first developed the theory of buoyancy?

Answer 65

Archimedes