Forces

Question 1

Hooke’s Law

Answer 1

The extension of a spring (or wire) is proportional to the applied load if the limit of proportionality is not exceeded

Question 2

Density

Answer 2

The density of a substance is defined as its mass per unit volume

Question 3

Pressure

Answer 3

Pressure is defined as the force per unit area, where the force is acting at right angles to the area

Question 4

Upthrust

Answer 4

The vertical upward force exerted on a body by a fluid when it is fully or partially submerged in the fluid, due to the difference in fluid pressure

Question 5

Archimedes Principle

Answer 5

The buoyant force (upthrust) on a submerged object is equal to the weight of the fluid that is displaced by the object

Question 6

Principle of Flotation

Answer 6

A floating object displaces a weight of fluid equal to its own weight

Question 7

Equilibrium

Answer 7

The resultant force on the object is zero

The resultant moment (or torque) on the object about any axis is zero

Question 8

Principle of Moments

Answer 8

For a body in rotational equilibrium, the sum of all the clockwise moments about any axis must equal the sum of all the anticlockwise moments about the same axis

Question 9

Moment

Answer 9

The moment (or torque) of a force about a point is defined as the product of the force and the perpendicular distance from the point to the line of action of the force

Question 10

Couple

Answer 10

A couple consists of a pair of equal and opposite parallel forces whose lines of action do not coincide

Question 11

Torque of Couple

Answer 11

Torque of a couple is defined as the product of one force and the perpendicular distance between the two forces

Question 12

Centre of Gravity

Answer 12

The point at which its weight or the resultant of the distributed gravitational attraction on the body appears to act