Moments, levers and gears

Question 1

Moment

Answer 1

The turning effect of a force
A measure of an objects tendency to rotate when a force is applied

Question 2

What are clockwise and anticlockwise moments?

Answer 2

When the movement caused by a moment is anti-clockwise, it is an anti-clockwise moment
When the movement caused by a moment is clockwise, it is a clockwise moment

Question 3

Pivot/ fulcrum

Answer 3

A point where something can rotate or turn around

Question 4

Perpendicular distance

Answer 4

The shortest distance between the pivot and the line of action of the force

Question 5

Line of action

Answer 5

Representation of how the force is applied using lines

Question 6

How to calculate a moment?

Answer 6

Moment (Nm) = force (N) x perpendicular distance to the pivot (m)

Question 7

What is the moment of a balanced object?

Answer 7

The clockwise moment = anti-clockwise moment

Question 8

What are levers?

Answer 8

A tool used to transmit the turning effect of the force
Used so we apply an input force, and the lever creates a larger output force so we don’t have to do as much work

Question 9

Examples of levers

Answer 9

Scissors
See saws
Wheelbarrows
Spanner/hammer and a nut

Question 10

What happens to input and output forces if they are on different sides of the pivot?

Answer 10

They work in different directions, like in scissors

Question 11

What happens to input and output forces if they are on the same side of the pivot?

Answer 11

Act in the same direction eg in a wheelbarrow

Question 12

Why is the output force closer to the pivot than the input force?

Answer 12

So the output force is stronger, which is the whole point of a lever
Shown in the equation force = momentxdistance

Question 13

Work

Answer 13

When a force is done on an object energy is transferred
Eg pushing a box transfers kinetic energy to thermal energy in friction

Question 14

Elastic material

Answer 14

Applying more than 1 force to compress or stretch an object then returns to its original shape

Question 15

Force needed to stretch object

Answer 15

Spring constant x extension/compression

Question 16

What happens when material is stretched?

Answer 16

We do work by transferring energy
And storing it as elastic potential energy

Question 17

How to work out weight of object based on extension caused?

Answer 17

Measure extension of spring to line on graph then to the weight

Question 18

Extension and weight with a spring and rubber band

Answer 18

Spring = Directly proportional and a linear relationship
Rubber band = s shape and non linear relationship

Question 19

Adding too much weight

Answer 19

Extension no longer linear because overstretched
So not return to original shape
= exceeded limit of proportionality

Question 20

Inelastic deformation

Answer 20

Won’t return to original shape

Question 21

Particles in a fluid

Answer 21

Exert a force at right angles to the container

Question 22

Pressure unit

Answer 22

Pa

Question 23

Pressure equation

Answer 23

Normal to surface (N) / area of that surface (m2)

Question 24

Pressure in a liquid container

Answer 24

Higher at the bottom
Because greater weight of liquid acting downwards
And so greater density of liquid

Question 25

Object float or sink

Answer 25

Bottom of object has larger pressure than top as it has a higher depth So larger force on bottom than too Resultant force UP = upthrust It will float if upthrust = weight It will sink if upthrust = less than weight

Question 26

Why does water rise when object put in?

Answer 26

Because it is displaced by the object

Question 27

Size of upthrust and displacement

Answer 27

Size of upthrust acting on object is the same as water displaced by the object