Ask a New Question
Menu

Recall that the formula for momentum is:

P=mv
Which of the following correctly shows momentum being calculated?
Responses

45 N=(9 kg) (5 m/s)

45 N = ( 9 kg ) ( 5 m / s )

14 kg*/s=(9 kg) (5 m/s)s

4 kg*m/s=(9 kg) (5 m/s)

3 answers

To calculate momentum using the formula \( P = mv \), where \( P \) is momentum, \( m \) is mass, and \( v \) is velocity, we need to ensure that the units are correctly represented and consistent.

Here, momentum units should be in kg·m/s (kilograms multiplied by meters per second). Let's examine each option given:

  1. 45 N = (9 kg) (5 m/s)

    • This is incorrect because the left side (45 N) represents force, not momentum.

  2. 45 N = (9 kg) (5 m/s)

    • Identical to the first option, and also incorrect for the same reason.

  3. 14 kg/s = (9 kg)(5 m/s)

    • This is incorrect. The left side's units (kg/s) do not correspond to momentum.

  4. 4 kg*m/s = (9 kg)(5 m/s)

    • This option contains an error. To calculate momentum for \((9 \text{ kg}) (5 \text{ m/s})\), the calculation is \(9 \cdot 5 = 45\), so the correct momentum should be \(45 \text{ kg·m/s}\), not \(4 \text{ kg·m/s}\).

From the options given, none correctly show the calculation of momentum. The momentum \( P \) should be: \[ P = (9 \text{ kg}) (5 \text{ m/s}) = 45 \text{ kg·m/s}. \]

So, the correct expression should reflect that the momentum is \( 45 \text{ kg·m/s} \). You might want to recheck the options to find the correct formulation.

A hockey puck with a mass of 0.12 kg is traveling across the ice at a velocity of 150 m/s downfield. What is the momentum of the hockey puck?(1 point)
Responses

P=18 N

P=18 kg*m/s

P=8*10−4 kg*m/s

M=18 kg*m/s

To find the momentum \( P \) of the hockey puck, we can use the formula:

\[ P = mv \]

Where:

  • \( m \) is the mass of the puck (0.12 kg),
  • \( v \) is the velocity (150 m/s).

Now let's calculate the momentum:

\[ P = (0.12 , \text{kg}) \times (150 , \text{m/s}) = 18 , \text{kg} \cdot \text{m/s} \]

Now, let's evaluate the provided responses:

  1. P = 18 N

    • This is incorrect because Newton (N) is a unit of force, not momentum.

  2. P = 18 kg*m/s

    • This is correct! This represents the momentum of the hockey puck.

  3. P = 8 * 10^{-4} kg*m/s

    • This is incorrect. It is a very small value compared to the actual momentum calculated.

  4. M = 18 kg*m/s

    • This is incorrect notation. It should be \( P = 18 , \text{kg} \cdot \text{m/s} \) instead of \( M \).

The correct response is:

P = 18 kg*m/s