Question

Multiple choiceeeeee homework A 70kg boy is standing at rest on a ice skating rink (assume it's a frictionless surface) gets hit in the face by ahuge 3.5 kg snowball moving at 15 m/s. The snowball sticks to his face. At what speed is the snowball coveredboy traveling after the collision?

Answer 1

Given:

The mass of the boy, M=70 kg

The mass of the snowball, m=3.5 kg

The speed of the snowball before hitting the boy, v=15 m/s

To find:

The speed of the snowball-covered boy after the collision.

Step-by-step explanation:

From the law of conservation of momentum, the total momentum of a system always remains the same. Thus the total momentum of the boy and the snowball before the collision must be equal to the total momentum of the boy and the snowball after the collision.

Thus,

`\begin{gathered} mv=(m+M)u \\ \Rightarrow u=(mv)/((m+M)) \end{gathered}`

Where u is the velocity of the snowball-covered boy after the collision.

On substituting the known values,

`\begin{gathered} u=(3.5*15)/(3.5+70) \\ =0.71\text{ m/s} \end{gathered}`

Final answer:

The speed of the snowball-covered boy after the collision is 0.71 m/s

Thus the correct answer is option B.