Question

You live 40 km from the high school. If your car has an average force of friction of 8000 newtons of force then how much energy does it take for you to get to school? If you drive at an average speed of 20 m/s then how much power do you use to get to school

Answer 1

`E=3.2\ 10^8\ Joule`

`P=160,000W=160KW`

Step-by-step explanation:

Work and energy

Those are closely related concepts. Work is the product of force by displacement if they have the same direction (parallel). Work transfers energy from one form to another, or from one place to another.

Part 1

The average force of friction of the car is 8,000 N, driven for a distance of 40 Km = 40,000 m. The work done (and the energy transferred) by the car in the travel is

`E=W=F.d=8,000 N. 40,0000 m =3.2\ 10^8Joule`

Part 2

Knowing the average speed of the car, we can compute the average power of the car when driving to school with the formula

`\displaystyle P=(W)/(t)=(F.d)/(t)=F.v`

This assumes the speed is constant throughout the distance traveled in a time t, thus

`P=8,000\ N\ .20\ m/s`

`\boxed{P=160,000W=160KW}`