Newton - second is the unit of

Options

A. Velocity
B. Angular momentum
C. Momentum
D. Energy

Answer

To determine what Newton-second is the unit of, we can analyze the options provided: velocity, angular momentum, momentum, and energy.

### Step-by-Step Solution:

1. **Understanding Newton's Second**:
- The unit of force is Newton (N), which is defined as \(1 \, \text{N} = 1 \, \text{kg} \cdot \text{m/s}^2\).
- Therefore, a Newton-second (N·s) can be expressed as:
\[ 1 \, \text{N} \cdot \text{s} = 1 \, \text{kg} \cdot \text{m/s}^2 \cdot \text{s} = 1 \, \text{kg} \cdot \text{m/s} \]

2. **Analyzing Each Option**:
- **Velocity**: The unit of velocity is meters per second (m/s). This does not relate to Newton-seconds, so this option is incorrect.
- **Angular Momentum**: The formula for angular momentum (L) is given by:
\[ L = m \cdot v \cdot r \]
where \(m\) is mass (kg), \(v\) is linear velocity (m/s), and \(r\) is the radius (m). The unit of angular momentum is:
\[ \text{kg} \cdot \text{m}^2/\text{s} \]
This does not match with Newton-seconds.
- **Momentum**: The formula for momentum (p) is:
\[ p = m \cdot v \]
where \(m\) is mass (kg) and \(v\) is velocity (m/s). The unit of momentum is:
\[ \text{kg} \cdot \text{m/s} \]
This matches with the unit of Newton-seconds, confirming that Newton-second is indeed a unit of momentum.
- **Energy**: The unit of energy (work) is given by:
\[ \text{Work} = \text{Force} \cdot \text{Distance} = \text{N} \cdot \text{m} = \text{kg} \cdot \text{m}^2/\text{s}^2 \]
This does not match with Newton-seconds.

3. **Conclusion**:
- After analyzing all options, we conclude that Newton-second is the unit of momentum.

### Final Answer:
**Newton-second is the unit of momentum.**