Mechanics

Question 1

Define the moment of a force about a pivot

Answer 1

The turning effect of a force. Force X perpendicular distance of the force from the pivot

Question 2

State the conditions necessary for a body to be in equilibrium

Answer 2

Vector sum of forces is zero, so there is no resultant force. Sum of moments about a particular point is zero, so there is no resultant moment.

Question 3

State the principle of conservation of momentum

Answer 3

The total momentum before a collision is equal to the total momentum after the collision in an isolated system.

Question 4

What is a couple?

Answer 4

Couple is a pair of equal and opposite coplanar forces.
Moment of couple is force × perpendicular
distance between the lines of action of the forces.

Question 5

What is terminal speed?

Answer 5

The speed reached when the upward force will equal the weight of the object. As there is no net force on the object the acceleration will be zero. The object will fall at a constant velocity

Question 6

What is Newton’s first law of motion?

Answer 6

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Question 7

What is Newton’s second law of motion?

Answer 7

The acceleration of an object is directly proportional to the resultant force acting on it, and inversely proportional to its mass. F=ma

Question 8

What is Newton’s third law of motion?

Answer 8

If object A exerts a force on object B, then object B exerts an equal and opposite force of the same type on object A