Forces and energy

Question 1

How does a bulb transfer energy?

Answer 1

Electricity transfers energy to an electric bulb which then transfers the energy to the surroundings by light and heating

Question 2

What is work done?

Answer 2

Energy transferred by a force

Question 3

What does the amount of work done depend on?

Answer 3

The size of the force and how far the force has moved

Question 4

What is power?

Answer 4

The rate at which energy is transferred

Question 5

What is the relationship between watts and joules?

Answer 5

1 watt is one joule of work per second

Question 6

What is a contact force?

Answer 6

the force between two touching objects

Question 7

What is the normal contact force?

Answer 7

An object at rest on a surface exerts a force on the surface. The reaction force acts at right angles to the surface called the normal contact force

Question 8

What is water resistance a form of?

Answer 8

friction

Question 9

If a boat is moving what forces is it experiencing?

Answer 9

• Water resistance
• Force from the engine
• Upthrust
• Gravity

Question 10

What is upthrust balanced out by?

Answer 10

Gravity (non-contact force)

Question 11

What is gravity?

Answer 11

A force that occurs between any two objects that have mass

Question 12

Why does the moon stay in orbit around the Earth?

Answer 12

Because the two bodies are attracting each other (force of the moon on the earth is the same size of the force of the earth on the moon in the opposite direction)

Question 13

What are vectors (in this instance)

Answer 13

Arrows that show both magnitude and direction (in showing the forces of gravity between two bodies)

Question 14

What is an action-reaction force?

Answer 14

Pairs of forces acting on different objects, in opposite directions

Question 15

What is a force field?

Answer 15

A space around an object where it can affect other objects

Question 16

What are forces that affect objects they’re not in direct contact with

Answer 16

Magnetism

Static Electricity

Question 17

What is a magnetic field?

Answer 17

The space around other materials where it can affect other materials

Question 18

What is an electric field?

Answer 18

An object that is electrostatically charged’s area around it which can affect other objects in that area (two objects close to each other in the field with the same charge produce equal and opposite directional forces)

Question 19

If the resultant force is zero, what does this mean?

Answer 19

The forces acting on the object are balanced

Question 20

What happens to the forces on an aeroplane travelling at a constant force?

Answer 20

The horizontal and vertical forces are equal and the resultant force is 0

Question 21

What is a free body force diagram?

Answer 21

A diagram to model the forces acting on an object

Question 22

When do we use scale diagrams?

Answer 22

When you need to find the resultant force in an instance that the forces acting on an object are not acting along the same line

Question 23

How do you draw a scale diagram?

Answer 23

1. Draw arrows at the correct angles to represent the forces (the length should represent the size of the force (use a scale))
2. Draw lines to make a parallelogram
3. The resultant force is the diagonal of the parallelogram and measure this line and use the scale to find the resultant force

Question 24

What helps an aeroplane to fly steeper?

Answer 24

Thrust

Question 25

How can you work out the amount of thrust is pushing the aeroplane upwards and forwards?

Answer 25

By resolving the thrust force into two component forces at right angles to each other (using a scale diagram)

Question 26

How do you draw a scale diagram to help with resolving a force (e.g thrust)

Answer 26

1) Draw a force arrow (e.g thrust) to scale at the correct angle (e.g 30 degrees at 200kN)
2) Draw a rectangle with the sides in the direction you are interested in e.g horizontal or vertical
3) The line lengths that line up with the force line (in out example 200kN) and measure - use the scale to find size

Question 27

What is a moment?

Answer 27

A turning force

Question 28

What does the moment of a force depend on?

Answer 28

The size and where the force is applied - greater the force and the further away it is from the pivot (the point around which the object can rotate) the greater the moment

Question 29

What is the normal?

Answer 29

The distance between the force and the pivot, right angle to the direction of the force

Question 30

What is the unit for moment?

Answer 30

Newton metres (N m)

Question 31

What does it mean when a system involving rotational forces are in equilibrium?

Answer 31

The sum of the clockwise movements = the sum of the anticlockwise movements

Question 32

What is a lever?

Answer 32

A bar that pivots about a point and is used to transfer a force

Question 33

What is effort?

Answer 33

Force from a man onto a lever

Question 34

What is the load?

Answer 34

Force of object on lever

Question 35

How do gears turn other gears?

Answer 35

The teeth of one gear fits into another and so as one moves, so does the other

Question 36

If one gear as 8 times as many teeth as the second, how many turns will it take of the smaller for one rotation of the larger one

Answer 36

8 turns of the smaller one for one rotation of the larger