forces in action

Question 1

what is a free body diagram

Answer 1

used to show relative magnitude and direction of all forces on an object

Question 2

how is a free body diagram drawn

Answer 2

the forces are arrows,
the size shows the magnitude of the force
the direction shows the direction of the force
the object is usually a square
each force is labelled

Question 3

what is the moment of a force

Answer 3

the turning effect created by a force

Question 4

what is a couple

Answer 4

a pair of equal and opposite coplanar forces. it has a turning effect but no resultant force

Question 5

define coplanar

Answer 5

when two things are on the same plane

Question 6

what the principle of moments

Answer 6

when in equilibrium the sum of the clockwise moments and anticlockwise moments are equal

Question 7

what is the centre of mass

Answer 7

a point on an object where all the mass appears to be. its where the weight appears to act

Question 8

what causes an object to fall

Answer 8

if the centre of mass is outside the base it will fall.

if it’s over a surface’s edge it will fall off the surface

Question 9

wheres the centre of mass of an object hanging from a string

Answer 9

directly below the the point it’s hung from

Question 10

define plane lamina

Answer 10

a perfectly flat object

Question 11

what is Archimedes principle

Answer 11

an object in a fluid will experience an upthrust equal to the weight of the fluid displaced (gas or liquid)