POINTS TO REMEMBER 1. Newton's I^st Law of motion states that every body has tendency to oppose any change in its state of motion. This property of objects is called Inertia.
2. Inertia is of three types (i) Inertia of rest (ii) Inertia of motion and (iii) Inertia of direction.
3. Inertia ∝ mass.
4. Linear momentum = m
5. Newton's IIndlaw of motion states that rate of change of momentum is equal to applied force.
= = m
1 Newton = 10⁵dyne
6. Newton's Istand IIIrdlaw can be derived from second law therefore IIndlaw is the most fundamental law out of the three law.
7. Impulse = Δt = Δ=
8. According to law of conservation of linear momentum :
Initial Momentum = Final Momentum
m₁u₁+ m₂u₂ = m₁v₁+ m₂v₂

9. Thrust on rocket

according as gravity is present or absent.
10. Acceleration of rocket

according as gravity is present or absent.
11. For equilibrium of a body under the action of concurrent forces = 0
12. Apparent weight of a body in the lift accelerated up is W = m (g + a).
13. Apparent weight of a body in the lift accelerated down is W = m (g – a)
14. If the downward acceleration of the lift is a = g, then W = 0 i.e. the body will enjoy weightlessness.
15. If the downward acceleration of the body is a > g, then W is negative, the body will rise up to the ceiling of lift.