Chapter 4 Forces

Question 1

Field of force

Answer 1

A region of space in which a force acts on a body

Question 2

Center of gravity

Answer 2

A point where is the entire weight of the body may be considered to act

Question 3

What affects magnitude of viscous force

Answer 3

Relative speed
Shape of body
Cross section area relative to motion of body
Texture of body surface
Viscosity of fluid

Question 4

Hooke’s law

Answer 4

Extension are compression of a body is directly proportional to the applied force provided that the limit of proportionality has not been exceeded

F = kx

Question 5

Translational equilibrium

Answer 5

Sum of forces acting on the object in any direction is zero

Question 6

Moment of force

Answer 6

Product of the force and the perpendicular distance of the line of action of the force to the pivot

Question 7

Couple

Answer 7

Two opposite forces acting on the same body in same magnitude but opposite directions cause line of action do not coincide

Question 8

Torque of a couple

Answer 8

Product of one of the forces and the perpendicular distance between the forces

Question 9

Rotational equilibrium

Answer 9

There is no resultant torque about any point

Question 10

Principle of moments

Answer 10

Principle of moments states that for an object to be in rotational equilibrium some of clockwise moments about any point must be equal to some of anticlockwise moments about that same point

Question 11

Equilibrium

Answer 11

Translational and rotational equilibrium (need to state both)

Question 12

Pressure

Answer 12

Force acting normally (perpendicularly) per unit area of a surface

Question 13

Upthrust

Answer 13

Net upwards force exerted by a fluid on a submerge of floating object. It arises due to the difference in pressure between the upper and lower surfaces of the object

Question 14

Archimedes principle

Answer 14

Upthrust is equal in magnitude an opposite in direction to the weight of fluid displaced by the submerged or floating object