# Topic 5 - Forces Flashcards

1
Q

What effect does gravity have

A

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

2
Q

What is the mass of something

A

The amount of matter in an object

3
Q

What is the weight of something

A

-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

4
Q

How does the location of gravitational field vary its strength

A

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

5
Q

Why does the weight of an object depend on its location

A

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

6
Q

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

A

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.

7
Q

What is weight measured in.

A

Newtons (N)

8
Q

Where does the weight of an object act

A

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

9
Q

How is weight measured

A

Using a calibrated spring balance or newtonmeter

10
Q

What is mass measured by and what is its units

A

It’s measured in kilograms with a mass balance

11
Q

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

A

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

12
Q

What is the link between weight and mass

A

They are directly proportional

13
Q

How do you write that weight and mass are directly proportional

A

W ∝ M

14
Q

What happens when a force moves an object through a distance

A

Energy is transferred and work is done on the object

15
Q

What must there be to make something move

A

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

16
Q

What does force do to move an object

A

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

17
Q

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

A

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.

18
Q

How do you find out how much work is being done

A

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

19
Q

How can joules be converted to newton metres

A

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

20
Q

What can happen when you apply a force to an object

A

It may cause it to stretch, compress or bend

21
Q

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

A

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

22
Q

What makes an object be elastically deformed

A

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

23
Q

What are elastic objects and give an example

A

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

24
Q

What is an object that has been inelastically deformed

A

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