Turning forces and centre of gravity

Question 1

How is the moment calculated?

Answer 1

moment = force X distance from the fulcrum

Question 2

what is a lever?

Answer 2

A lever is a rigid body which is free to rotate about a fixed point called a fulcrum

Question 3

give an example of a fulcrum

Answer 3

eg the middle of a see saw would be called
a fulcrum

Question 4

What is a fulcrum?

Answer 4

the pivot about which a lever turns

Question 5

give three examples of levers

Answer 5

Examples of levers: Door, door handle, scissors.

Question 6

what is the moment of a force?

Answer 6

how much the force can turn an object

Question 7

what does the law of the lever state?

Answer 7

The law of the lever states that when a lever (eg metre stick) is balanced the sum of the clockwise moments equals the sum of the anticlockwise moments.

Question 8

how do we know when something is balanced?

Answer 8

when the clockwise moments = the anti-clockwise moments

Question 9

what is the centre of gravity of an object?

Answer 9

The centre of gravity of an object is the point through which all the weight of the object appears to act. ie the centre of its weight.

Question 10

give an example showing the centre of gravity

Answer 10

Eg you can balance a pen on your finger if you place your finger at the centre of gravity, if not the pen will fall)

Question 11

what are the requirements for an object to be stable under gravity?

Answer 11

The centre of gravity should be as low as possible.

The area of the base should be as large as possible.

Question 12

name the three states of equilibrium

Answer 12

stable
unstable
neutral

Question 13

how many states of equilibrium are there?

Answer 13

3

Question 14

what do we call it when an object is balanced?

Answer 14

it is in equilibrium

Question 15

what is equilibrium?

Answer 15

when something is balanced

Question 16

how do we know if an object is in stable equilibrium?

Answer 16

An object is in stable equilibrium if it does not topple easily when a small force is applied to it.

Question 17

how do we know if an object is in unstable equilibrium?

Answer 17

An object is in unstable equilibrium if it will topple easily when a small force is applied to it.

Question 18

do the experiment to find centre of gravity of irregular shaped cardboard

Answer 18

.

Question 19

how do we know when something is in neutral equilibrium?

Answer 19

if when a small force is applied to it it’s centre of gravity does not change e.g a perfect sphere rolling

Question 20

what is a plumbline?

Answer 20

a cord from which a metal weight is suspended pointing directly to the earth’s centre of gravity