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An ice hockey puck with a mass of 0.19 kg collides inelastically with a 0.85 kg snowball that is sliding to the left with a speed of 0.70 m/s. The combined puck and snowball slide along the ice with a velocity of 4.2 m/s to the right. What is the velocity of the hockey puck before the collision?

User Suing
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1 Answer

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Answer:

0.15 m/s

Step-by-step explanation;

The collision is inelastic, which means only momentum is conserved.

Now, before the collision the momentum of the system is


p_{in\text{ital}}=(0.19\operatorname{kg})v+(0.85\operatorname{kg})\cdot0.70_{}(m/s)_{}

After the collision the momentum becomes


p_{\text{fInal}}=(0.19\operatorname{kg}+0.85\operatorname{kg})\cdot4.2
=0.728(kg\cdot m/s)

The conservation of momentum demands that


p_{\text{Iniital}}=p_{\text{fInal}}

therefore, we have


(0.19\operatorname{kg})v+(0.85\operatorname{kg})\cdot0.70(m/s)_{}=0.728(kg\cdot m/s

Neglecting the units for a while gives us


0.19v+0.70=0.728

subtracting 0.70 from both sides gives


0.19v=0.728-0.70
0.19v=0.028

finally, dividing both sides by 0.19 gives and rounding the nearest hundredth gives


\boxed{v=0.15.}

Hence, the velocity of the hockey puck before the collision is 0.15 m/s.

User Alioguzhan
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