Formative Practice 2.5 – Physics Form 4 Chapter 2 (Force and Motion I)

Question 1:
 What is meant by momentum and conservation of momentum?

Answer:
Mementum (p) is product of the mass (m) of an object and its velocity (v).

p = mv

The Principle of Conservation of Momentum states that the total momentum before collision is equal to the total momentum after collision if no external force is acting on it.

Question 2:
A lorry of mass 1 000 kg moves at a velocity of 5.0 m s^–1. It collides with a car of mass 800 kg moving at a velocity of 2.0 m s^–1 in the same direction. If the lorry moves at a velocity of 3.4 m s^–1 in the same direction aft er the collision, calculate the velocity of the car.

Answer:


$$\begin{aligned} m_1 u_1+m_2 u_2 & =m_1 v_1+m_2 v_2 \\ 1000(5.0)+800(2.0) & =1000(3.4)+800\left(v_2\right) \\ 5000+1600 & =3400+800 v_2 \\ 800 v_2 & =5000+1600-3400 \\ 800 v_2 & =3200 \\ v_2 & =\frac{3200}{800} \\ v_2 & =4 \mathrm{~ms}^{-1} \end{aligned}$$