Q20DQ - University Physics with Modern Physics

Question

A car speeds up while the engine delivers constant power. Is the acceleration greater at the beginning of this process or at the end? Explain.

Step-by-Step Solution

Answer

The acceleration is greater at the beginning.

Step 1: Determination of power when the car speeds up

The power is given by;

$\mathrm{P}=\mathrm{f}\times \mathrm{v}$ 

Here, P is the power, f is the force acting and v is the average velocity of the car.

Step 2: Explanation of the reason why acceleration is greater at the beginning

For very small instances,

P at an instant = force x velocity

From the above formula it can be stated that as the velocity increases, the force acting on the car decreases since the power given is constant.

So, in the beginning, there is more force as compared to at the end.

Thus, acceleration is greater at the beginning of the process.