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

Given:-

• Mass of ball (M) = 200g

• Initial velocity (u) = 10m/s

• Final velocity (v) = -10m/s (Because it is given that the speed of ball remain same in both condition & minus sign denotes the ball is moving in opposite directions).

To Calculate:-

• Change in momentum

Solution:-

As we know that the rate of change of momentum is final momentum - initial momentum.

Convert the mass of ball into kg

1 kg = 1000g

∴ 200g = 200/1000 = 0.2 kg

Firstly we calculate the initial momentum of the ball .

→ m = Mu⠀

Substitute the value we get

→ m = 0.2×10

→ m = 2kg m/s

∴ The initial momentum of the ball is 2kg m/s.

Now Calculating the final momentum

→ m = Mv

Substitute the value we get

→ m' = 0.2×(-10)

→ m' = -2kg m/s

∴ The Final momentum of the ball is 2kg m/s.

→ Rate of change of momentum = Final momentum- Initial momentum

Substitute the value we get

→ Change in momentum = m' -m

→ chnage in momentum = -2-2

→ change in momentum = -4kg m/s.

∴ The change in momentum of the hockey ball is -4kg m/s.

Answer 2

Answer:

Given:-

Mass of ball (M) = 200g

Initial velocity (u) = 10m/s

Final velocity (v) = -10m/s (Because it is given that the speed of ball remain same in both condition & minus sign denotes the ball is moving in opposite directions).

To Calculate:-

Change in momentum

Solution:-

As we know that the rate of change of momentum is final momentum - initial momentum.

Convert the mass of ball into kg

1 kg = 1000g

∴ 200g = 200/1000 = 0.2 kg

Firstly we calculate the initial momentum of the ball .

→ m = Mu⠀

Substitute the value we get

→ m = 0.2×10

→ m = 2kg m/s

∴ The initial momentum of the ball is 2kg m/s.

Now Calculating the final momentum

→ m = Mv

Substitute the value we get

→ m' = 0.2×(-10)

→ m' = -2kg m/s

∴ The Final momentum of the ball is 2kg m/s.

→ Rate of change of momentum = Final momentum- Initial momentum

Substitute the value we get

→ Change in momentum = m' -m

→ chnage in momentum = -2-2

→ change in momentum = -4kg m/s.

$\tt \pink{∴ The \: change \: in \: momentum \: of \: the \: hockey \: ball \: is \: -4kg \: m/s.}$