Question

A car travels at a constant velocity of 20.0 meters/second for 15 seconds. What is the power of the car if the initial force applied to it was 95 newtons?

Answer 1

Work done by the force = Force x displacement. Power = work done/time = F.s/t = F.u.t/t = F.u = 95 x 20 = 1900J. {S=ut because acceleration is zero since car is moving at constant velocity}.

Answer 2

The correct answer to the question is 1900 Joule.

CALCULATION:

As per the question, the velocity of the car v = 20.0 m/s.

The time taken by the car t = 15 seconds.

The initial force applied on the car F = 95 N.

We are asked to calculate the power of the car.

Let the displacement of the car is denoted as S.

Let the power of the car is P.

The power of a car is defined as the word done by the car per unit time.

Hence, the power P =
`(W)/(t)`

=
`(\vec F.\vec S)/(t)`

=
`\vec F.(S)/(t)`

=
`\vec F.\vec v`

=
`Fvcos\theta`

Here,
`\theta` is the angle between force and velocity.

If
`\theta= 0^(0)`, then P = Fv.

Hence, the power of the car is calculated as -

P = 95 N × 20.0 m/s

= 1900 Joule.