Moments And Centre Of Gravity

Question 1

What is a moment of a force?

Answer 1

The turning effect of a force

Question 2

How do you calculate the moment of a force?

Answer 2

Force
X
(perpendicular distance from the force to the fulcrum)

Question 3

What is lever?

Answer 3

A lever is any rigid body that is free to run about a fixed point or axis called a fulcrum

Question 4

What is the law of the lever?

Answer 4

When a lever is balanced by any number of forces, the sum of the clockwise moments acting on it is equal to the sum of the anti clockwise moments

Question 5

How do you investigate the law of the lever?

Answer 5

1. Tie a string around the centre of a metre stick and hang it from a retort stand. Make sure it is balanced
2. Hang a 1 N weight on the left side and a 2 N weight on the right side in a position at which the metre stick is balanced
3. Calculate the moment of each weight
4. Repeat with several different weights

Question 6

What is the centre of gravity?

Answer 6

The centre of gravity of an object is the point through which the weight of an object appears to act

Question 7

How do you find the centre of gravity of an irregular shaped picture piece of cardboard?

Answer 7

1. Make 3 or 4 small holes in the edge of the cardboard piece and stick a pin through the cardboard to a cork held by the clamp of a retort stand
2. Hang the plumbline from the pin freely and allow the system to come to rest before marking two points behind the plumbline on the cardboard with Xs
3. Repeat using the other holes in the cardboard
4. Join the lines between each pair of Xs, the point at which they all intersect is the centre of gravity

Question 8

What is equilibrium?

Answer 8

An object that is balanced is said to be in equilibrium

Question 9

What factors help stability?

Answer 9

A low centre of gravity

A wide base