c05 turning effects of forces

Question 1

definition of moment of a force

Answer 1

The moment of a force/torque about a pivot is the product of the force and the perpendicular distance from the pivot to the line of action of the force.

Question 2

formula for moment of a force

Answer 2

M=Fd

Question 3

definition of principle of moments

Answer 3

States that when a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot.

Question 4

definition of centre of gravity

Answer 4

An imaginary point where the entire weight of the object seems to act. (can be outside of the object)

Question 5

definition of stability

Answer 5

Measure of an objects ability to return to its original position

Question 6

factors affecting stability

Answer 6

Position of centre of gravity
Base area of the object

Question 7

how to find the centre of gravity of a non-uniform object

Answer 7

Make three small holes on the edges as far away from one another as possible

Pin the object through one of the holes and hang a plumb line from the pin

Mark the top and bottom of the plumb line on the object

Join the markings from top to bottom with a dotted line

Repeat the steps until you have 3 dotted lines that cross at a point, which is the centre of gravity of the object

Question 8

what are some precautions when finding the centre of gravity of a non-uniform object

Answer 8

Switch off the fan

Use a thin thread for the plumb line

Ensure the plumb line is not swinging when marking the points but ensure the object is still swinging freely as frictional force between the pin and object may affect the equilibrium position