Dynamics

Question 1

Mass

Answer 1

measure of the quantity of matter of a body

property of a body which resists change in motion

Question 2

Weight

Answer 2

gravitational force acting on an object

W = m g

Question 3

Momentum

Answer 3

product of mass and the velocity of the body

p = m v

p momentum [ N s or kg m s⁻¹]

Question 4

Newton’s first law

Answer 4

A body remains at rest or continues to move in a straight line with a constant velocity unless a net external force acts on it

ΣFnet = 0 , Vf = Vi

Question 5

Newton’s second law

Answer 5

The rate of change of momentum of a body is directly proportional to the net external force acting on the body and takes place in the direction of the force

ΣF = δp/δt

Question 6

Impulse, I of the Force F

Answer 6

product of the force and time of impact

Δp

area under F-t graph

Question 7

Newton’s third law

Answer 7

The forces of action and reaction between interacting bodies are :

1. equal in magnitude
2. opposite in direction
3. of the same type
4. act on different bodies

Question 8

Principle of Conservation of Momentum

Answer 8

The total momentum of a system is constant if net external force acting on it is zero

Δp = 0 , ΣF =0

Question 9

Inelastic collisions

Answer 9

total momentum of a closed system is conserved

Pi = Pf

Question 10

Completely Inelastic collisions

Answer 10

two objects stick together after collision

total KE lost = maximum

Question 11

Elastic collisions

Answer 11

Conservation of total p and total KE

Pi = Pf

relative speed of approach = relative speed of separation
u₁ - u₂ = v₂ - v₁