Question

A hockey ball of mass 200g travelling at 10m/s is struck by a hockey stick so as to return it along its original path with a velocity at 5m/s. The magnitude of the change of momentum occured in the motion of the hockey ball by the force applied by the hockey stick is

Answer 1

$\textbf{\underline{\underline{According\:to\:the\:Question}}}$

★Given :-

m = 200 g

In kg = 0.2 kg

u = 10 m/s

v = -5 m/s

★Hence

$\textbf{\boxed{Initial\;momentum\;of\;ball}}$

= 0.2 kg × 10 m/s

= 2 kg m/s

$\textbf{\boxed{Final\;momentum\;of\;ball }}$

= 0.2 kg × (-5 m/s)

= -1 kg m/s

★Therefore

Change in momentum = Final momentum - Initial momentum

= -1kg m/s - 2kg m/s

= -3 kg m/s

★Here we have (-) implies that force applied by hockey is in the direction opposite to the original direction of motion.

$\boxed{\begin{minipage}{11 cm} Additional Information \\ \\ \ Final\;Velocity=Initial\; velocity+Acceleration\times Time \\ \\ Momentum = Mass\times Velocity \\ \\ Force=Mass\times Acceleration \\ \\ Force = \dfrac{Change\;in\;Momentum}{Time\;Interval} \\ \\ Impulse = Force\times Time \end{minipage}}$