P06 Forces in Equilibrium

Define ‘scalar’:

quantity with only magnitude

What is defined as ‘quantity with only magnitude’?

scalar

Define ‘vector’:

quantity with magnitude and direction

What is defined as ‘quantity with magnitude and direction’?

vector

Is velocity a vector or scalar?

vector

Is speed a vector or scalar?

scalar

Is mass a vector or scalar?

scalar

Is weight a vector or scalar?

vector

Is distance a vector or scalar?

scalar

Is displacement a vector or scalar?

vector

Is force a vector or scalar?

vector

Is acceleration a vector or scalar?

vector

What are the two ways to add vectors?

calculation, scale drawing

What is the opposite of adding vectors?

resolving vectors

What is the opposite of resolving vectors?

adding vectors

What is the trig function for the vertical component of a vector?

sin

What is the trig function for the horizontal component of a vector?

cos

What are the conditions for equilibrium?

sum of all forces acting on the object must be zero

Define ‘moment’:

force multiplied by perpendicular distance from line of action of force to the point

What is defined as ‘force multiplied by perpendicular distance from line of action of force to the point’?

moment

What equation links moment, force and distance?

moment\=Fd

Define ‘couple’:

pair of co-planar forces which are of equal magnitudes but act in opposite directions

What is defined as ‘pair of co-planar forces which are of equal magnitudes but act in opposite directions’?

couple

What equation links moment of a couple, force, and perpendicular distance between lines of actions of forces?

couple moment\=Fd

State the principle of moments:

for an object in equilibrium, sum of anticlockwise moments about a pivot equals sum of clockwise moments

Define ‘centre of mass’?

point at which an object’s mass appears to act

What is defined as ‘point at which an object’s mass appears to act’?

centre of mass

Where is the centre of mass of a uniform regular solid?

at its centre