Question

An automobile is moving at 72 kmph and is exerting attractive force of
4000N. What is the power of its engine?​

Answer 1

Given:

An automobile is moving at 72 kmph and is exerting attractive force of 4000N.

To find:

Power of the engine?

Calculation:

The power of any engine represents the instantaneous rate of doing work. Mathematically, it is represented by the ratio of the total work done and the total time taken.

However , it can also be represented as the product of force and velocity of the object.

All the values are to be put in SI units:

In order to convert unit of Velocity from km/hr to m/s , just multiply the value (in km/hr) with 5/18.

$\sf \therefore \: power = force \times velocity$

$\sf = > \: power = 4000\times (72 \times \dfrac{5}{18} )$

$\sf = > \: power = 4000\times (4 \times 5)$

$\sf = > \: power = 4000\times 20$

$\sf = > \: power = 80000$

$\sf = > \: power = 8 \times {10}^{5} \: watt$

So, power delivered by engine is 8 × 10⁵ watt.