Question

A hockey ball of mass 200 g hits on a hockey stick with a velocity 10 m/s. Calculate the change in momentum if the ball bounces back on the same path with the same speed.​

Answer 1

Answer:

$\large{\underline {\rm {\color{red}{Given :-}}}}$

• mass=200g

• velocity=10m/s

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$\large {\underline {\rm {\color{blue}{To \:Find :-}}}}$

•The change in momentum if the ball bounces back through the same path with same speed =?

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$\large {\underline {\rm {\color{orange}{Solution\::-}}}}$

$\begin{gathered}\\ \implies \sf \: mass = 200g = \frac{200}{1000} = 0.2kg \\ \\ \implies\boxed{ \sf\pink{mass = 0.2kg}} \\ \\ \implies \sf \: initial \: momentum = mu \\ \\ \implies \sf \: initial \: momentum = 0.2 \times 10 = 2kg \frac{m}{s} \\ \\ \implies \sf \: final \: momentum = mv \\ \\ \implies \sf \: final \: momentum = 0.2 \times 10 = 2kg \frac{m}{s} \\ \\ \implies \sf \therefore \: \: change \: in \: momentum = mv - mu \\ \\ \implies \sf \: change \: in \: momentum = - 2 - 2 \\ \\ \implies \sf \: \: change \: in \: momentum = - 4kg \frac{m}{s}\end{gathered}$

$\begin{gathered}\\ \implies\boxed{\sf\bold\pink{Change \: in \: momentum =-4kgms^{-1}}}\end{gathered}$

$\green\therefore$ Change in momentum is $\sf\red{-4kgm/s}$

Answer 2

Question:

A hockey ball of mass 200g hits on a hockey stick with a velocity of 10m/s. Calculate the change in momentum if the all bounces back on the same path with the same speed.

Required answer:

The change in momentum is – 4kg m/s.

Step–by–step explanation:

Given:

→ Mass of the ball : m : 200g

→ Initial velocity : u : 10m/s

→ Final velocity : v : – u : – 10m/s

Let's convert 200g into kg :

→ 1000g = 1kg

→ 200g = 200/1000

→ 200g = 0.2kg

We know that :

→ Change in momentum = (mv – mu)

→ ∆P = 0.2(– 10) – 0.2(10)

→ ∆P = – 2 – 2

→ ∆P = – 4

Therefore, the change in momentum of the hockey ball is – 4kg m/s.

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Note:

• We can see that the final velocity of the ball is negative.

• This is because the ball bounces back on the same path with the same speed.

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