Question

A 166-g hockey puck is gliding across the ice at 19.5 m/s. A player whacks it with her stick, sending it moving at 43.1 m/s at 45.0∘ to its initial direction of motion. What is the angle between the initial velocity of the puck and the force exerted on the puck? If stick and puck are in contact for 112 ms, what is the magnitude of the average force that was exerted on the puck?

Answer 1

Answer:

Explanation:

Given

mass of puck=166 gm

initial velocity=19.5 m/s

Final velocity=43.1 m/s at angle of $45^{\circ}$ to the intial direction

Suppose puck is travelling towards positive x axis

thus initial moment $\vec{P_i}=0.166\times 19.5\hat{i}$

Final momentum $\vec{P_f}=0.166\left ( 43.1cos45\hat{i}+43.1sin45\hat{j}\right )$

Impusle$=P_f-P_i=5.06\hat{i}+5.06\hat{j}-3.237\hat{i}$

$I=1.823\hat{i}+5.06\hat{j}$

Angle between initial velocity and force

$tan\theta =\frac{5.06}{1.823}$

$\theta =70.18^{\circ}$ w.r.t x-axis

and Fdt=Impulse

$dt=112 ms=112\times 10^{-3} s$

$\vec{F}=16.339\hat{i}+45.17\hat{j}$

$|F|=\sqrt{16.34^2+45.17^2}=48.03 N$