Question

A hockey puck with a mass of 0.18 kg travels at a velocity of 40 m/s toward a goalkeeper. The goalkeeper has a mass of 120 kg and is at rest. Assuming a closed system, find the total momentum of the puck before the puck is caught by the goalkeeper. (1 point)
Responses

0 kg.m/s
0 kg.m/s

7.2 kg.m/s
7.2 kg.m/s

6.4 kg.m/s
6.4 kg.m/s

-5.3 kg.m/s

Answer 1

To find the total momentum of the hockey puck before the goalkeeper catches it, we will calculate the momentum of the puck alone since the goalkeeper is at rest and has no initial momentum.

The momentum \( p \) of an object is given by the formula:

\[
p = m \cdot v
\]

where \( m \) is the mass of the object and \( v \) is its velocity.

For the hockey puck:

- Mass \( m = 0.18 \, \text{kg} \)
- Velocity \( v = 40 \, \text{m/s} \)

Calculating the momentum of the puck:

\[
p_{\text{puck}} = 0.18 \, \text{kg} \times 40 \, \text{m/s} = 7.2 \, \text{kg.m/s}
\]

Since the puck is moving toward the goalkeeper, we can consider this momentum to have a direction (for instance, to the right or forward), but since we are just asked for the total momentum before the puck is caught, the magnitude is sufficient.

Thus, the total momentum of the puck before it is caught by the goalkeeper is:

**7.2 kg.m/s**