Physics 2022 JAMB Past Questions - Question 21:  A car of mass 800kg attains a speed of 25m/s in 20 secs. The power developed in the engine is

Correct Answer

B

Explanation

To calculate the power developed by the engine, we can use the formula:

\[ \text{Power} = \text{Force} \times \text{Velocity} \]

First, we need to find the force acting on the car. We can use the equation:

\[ \text{Force} = \text{Mass} \times \text{Acceleration} \]

The acceleration can be found using the equation:

\[ \text{Acceleration} = \frac{\text{Change in Velocity}}{\text{Time}} \]

Given:
Mass (m) = 800 kg
Initial velocity (u) = 0 m/s (assuming the car starts from rest)
Final velocity (v) = 25 m/s
Time (t) = 20 s

\[ \text{Acceleration} = \frac{25 \, \text{m/s} - 0 \, \text{m/s}}{20 \, \text{s}} = 1.25 \, \text{m/s}^2 \]

Now, we can find the force:

\[ \text{Force} = 800 \, \text{kg} \times 1.25 \, \text{m/s}^2 = 1000 \, \text{N} \]

Finally, we can calculate the power:

\[ \text{Power} = \text{Force} \times \text{Velocity} = 1000 \, \text{N} \times 25 \, \text{m/s} = 25000 \, \text{W} \]

So, the power developed in the engine is 25000 watts.