Forces in Action

Question 1

centre of mass

Answer 1

a point in an object through which any externally applied force produces straight line motion with no rotation

Question 2

centre of gravity

Answer 2

the point through which the entire weight of the object can be said to act

Question 3

resultant force

Answer 3

the single force acting on an object when you have taken into account the individual forces acting on the object

Question 4

1 newton

Answer 4

force required for a 1kg mass to have an acceleration of 1ms^-2

Question 5

density

Answer 5

mass / volume

Question 6

moment of a force

Answer 6

force x perpendicular distance of the line of action from pivot

Question 7

principle of moments

Answer 7

when an object is in equilibrium the sum of clockwise moments about a point equals the sum of anticlockwise moments about the same point

Question 8

couple

Answer 8

pair of coplanar forces equal in size and acting in opposite directions

Question 9

torque of a couple

Answer 9

one of the forces x perpendicular distance between the forces

Question 10

conditions necessary for an object to be in equilibrium

Answer 10

net force is zero
net moment is zero

Question 11

Archimedes principle

Answer 11

the weight of fluid displaced is equal to the upthrust acting on an object that is either fully or partially submerged

Question 12

tension

Answer 12

the force experienced by a cable, rope, or string when pulled, hung, rotated, or supported

Question 13

drag

Answer 13

resistive force exerted by a fluid on an object moving through it