4.3 Moments

Question 1

what is mass?

Answer 1

the amount of matter in an object, measured in kg
the mass of an object doesnt change if the strength of the gravitational field changes

Question 2

what is weight?

Answer 2

the force experienced by a mass due to a gravitational force, measured in newtons
the weight of an object changes if the strength of the gravitational field changes

Question 3

what is the relationship between weight, mass and gravitational field strength?

Answer 3

weight = mass x gravitational field strength

Question 4

what is a moment?

Answer 4

the turning effect of a force around a turning point

Question 5

what is the relationship between moment of a force, size of force and perpendicular distance?

Answer 5

moment = force x perpendicular distance

Question 6

what is the principal of moments?

Answer 6

for a body to be in equilibrium, the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about any point

Question 7

what happens if moments arent balanced?

Answer 7

the object will turn

Question 8

why are levers useful?

Answer 8

they increase the distance from the pivot a force is implied, so you need less force to get the same moment

Question 9

what is a couple?

Answer 9

a pair of forces of equal size which act paralell to each other but in opposite directions

Question 10

does a couple cause a force?

Answer 10

a couple doesnt cause any resultant linear force, but produces a moment