Topic 5 - Forces

Question 1

What effect does gravity have

Answer 1

-On the surface of a planet it makes all things fall towards the ground
-It gives everything a weight

Question 2

What is the mass of something

Answer 2

The amount of matter in an object

Question 3

What is the weight of something

Answer 3

-The force acting on an object due to gravity (the pull of the gravitational forces on the objects)
-On earth this is caused by the gravitational field around the earth

Question 4

How does the location of gravitational field vary its strength

Answer 4

It’s stronger the closer you are to the mass causing the field, and stronger for larger masses.

Question 5

Why does the weight of an object depend on its location

Answer 5

Because the weight of an object depends on the strength of the gravitational field at the location of the object.

Question 6

Give an example of an object that weighs differently on the earth and on the moon

Answer 6

A 1kg weight will weigh around 1.6N on the moon but 9.8N on earth as the gravitational field strength on the moon is less.

Question 7

What is weight measured in.

Answer 7

Newtons (N)

Question 8

Where does the weight of an object act

Answer 8

It acts from a single point on the object, called it’s centre of mass

Question 9

How is weight measured

Answer 9

Using a calibrated spring balance or newtonmeter

Question 10

What is mass measured by and what is its units

Answer 10

It’s measured in kilograms with a mass balance

Question 11

What is the equation that links weight, mass and gravitational field strength

Answer 11

Weight (N) = Mass (kg) x Gravitational Field Strength (N/kg)

Question 12

What is the link between weight and mass

Answer 12

They are directly proportional

Question 13

How do you write that weight and mass are directly proportional

Answer 13

W ∝ M

Question 14

What happens when a force moves an object through a distance

Answer 14

Energy is transferred and work is done on the object

Question 15

What must there be to make something move

Answer 15

A force must be applied and the thing applying the forces needs a source of energy

Question 16

What does force do to move an object

Answer 16

It does ‘work’ and energy is transferred from one store to another

Question 17

Give an example of work being done when a forces moves something

Answer 17

When something is pushed along a rough surface work is being done against frictional forces and energy is being transferred to the kinetic energy store of the object because it starts moving. Some is also transferred to the thermal energy stores due to friction. This causes the overall temperature of the object to increase.

Question 18

How do you find out how much work is being done

Answer 18

Work done = Force x Distance
W (J) = F (N) x s (m)

Question 19

How can joules be converted to newton metres

Answer 19

1 J = 1Nm
One joule of work is done when a force of one newton causes an object to move a distance of one metre

Question 20

What can happen when you apply a force to an object

Answer 20

It may cause it to stretch, compress or bend

Question 21

Why do you need more than one force acting on an object to cause it to stretch, compress or bend

Answer 21

If it only had one force acting it would just move in the direction of the applied force

Question 22

What makes an object be elastically deformed

Answer 22

If it can go back to its original shape and length after the force has been removed

Question 23

What are elastic objects and give an example

Answer 23

Objects that can be elastically deformed (e.g. a spring)

Question 24

What is an object that has been inelastically deformed

Answer 24

If it doesn’t return to its original shape and length after the force has been removed