Question

A boy $P$ has a mass $20kg$ and its moving with a velocity of $5m{s}^{-1}$.Another boy $Q$ has a mass of $5kg$and is moving with a velocity of $20m{s}^{-1}$. Calculate the ratio of the momentum of $P$ and $Q$.

• A. 2:1
• B. 1:1
• C. 1:2
• D. 3:2

Answer 1

The correct option is B

1:1

Find the momentum of $P$and $Q$

Given:

A boy$\text{'}P\text{'}$ has mass $m_1=20kg$ and

velocity $v_1=5m{s}^{-1}$

Another boy $\text{'}Q\text{'}$has mass $m_2=5kg$ and

velocity $v_2=20m{s}^{-1}$

$$\begin{gathered} MomentumofP=m_1\times v_1 \\ P=20\times 5 \\ =100kgm/s \\ MomentumofQ=m_2\times v_2 \\ Q=5\times 20 \\ =100kgm/s \end{gathered}$$

Find the ratio of momentum:

The ratio of momentum is

$$\begin{gathered} \frac{P}{Q}=\frac{100kgm/s}{100kgm/s} \\ \frac{P}{Q}=\frac{1}{1} \end{gathered}$$

Thus, the ratio of momentum is $1:1$ (Option B).