Forces

Question 1

What is normal reaction force?

Answer 1

It is the force that the surface of one body exerts on the surface of another body it is in contact with, normal contact force is always perpendicular to the surface

Question 2

What is Hooke’s law?

Answer 2

Force applied is directly proportional to extension, if the limit of proportionality is not exceeded

Question 3

What is a couple?

Answer 3

A pair of equal forces parallel and opposite in direction which tend to produce rotation only

Question 4

What is upthrust?

Answer 4

It is the upward force acting on an body due to the pressure difference between the top and lower surfaces of an object when it is fully or partially submerged in a fluid, magnitude of upthrust is equals to weight of fluid displaced

Question 5

What is the origin of upthrust?

Answer 5

fluid pressure difference between the upper and lower surface of an object, pressure = force/area, upward force on the bottom surface is greater than downward force on the top surface hence a resultant upward force is created

Question 6

What is Archimedes’ principle?

Answer 6

Upthrust is equal to the weight of fluid displaced

Question 7

What is moment?

Answer 7

product of a force and perpendicular distance from the line of action of the force to the pivot

Question 8

What are the conditions for a system to be in equilibrium?

Answer 8

• Resultant force acting on the system in any direction is zero
• Resultant torque acting on the system about any axis is zero

Question 9

What is the principle of moment?

Answer 9

If a body is in equilibrium, the sum of all the clockwise moments about any axis is equals to the sum of all anticlockwise moments about the same axis

Question 10

What is the principle of floatation?

Answer 10

For an object floating in equilibrium, the upthrust is equal to the weight of the object