A body has a mass of 50 kg. Its velocity is brought down from 20 m/s to 5 m/s to m/s by a resisting froce in 5 seconds, the magnitude of resisting force is

Options

A. 750 N
B. 375 N
C. 150 N
D. 50 N

Answer

To solve the problem step by step, we will follow the principles of physics related to motion and force.

### Step 1: Identify the given data
- Mass of the body (m) = 50 kg
- Initial velocity (u) = 20 m/s
- Final velocity (v) = 5 m/s
- Time (t) = 5 seconds

### Step 2: Calculate the acceleration
To find the acceleration (a), we use the formula:
\[ a = \frac{v - u}{t} \]
Substituting the values:
\[ a = \frac{5 \, \text{m/s} - 20 \, \text{m/s}}{5 \, \text{s}} = \frac{-15 \, \text{m/s}}{5 \, \text{s}} = -3 \, \text{m/s}^2 \]
The negative sign indicates that the body is decelerating.

### Step 3: Calculate the resisting force
Using Newton's second law of motion, the force (F) can be calculated using the formula:
\[ F = m \cdot a \]
Substituting the values:
\[ F = 50 \, \text{kg} \cdot (-3 \, \text{m/s}^2) = -150 \, \text{N} \]
The negative sign indicates that the force is acting in the opposite direction to the motion of the body, which is expected for a resisting force. Therefore, the magnitude of the resisting force is:
\[ F = 150 \, \text{N} \]

### Final Answer
The magnitude of the resisting force is **150 Newtons**.

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