A car of mass 1000 kg is travelling at 15 m/s. The driver applies the brakes for 4 seconds, slowing the car to 5 m/s. What is the average power output of the brakes over the 4 seconds? Assume there are no other forces acting on the car.

Kinetic Energy, EK=(1/2)mv2. Energy is conserved, so the work done by the brakes, W, must be equal to the change in kinetic energy of the car, ∆EK. Therefore: W = ∆EK = (1/2)1000(152-52) = 0.51000200 = 100000 = 1*105J. Since power P = W/T, the average power output of the brakes is equal to the total work done by the brakes over the time that the brakes are applied for, therefore: P = 100000/4 = 25000W.

Answered by Adam H. Physics tutor

8319 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

How do I work out the efficiency of a process from a Sankey diagram?


A wave with a constant velocity doubles its frequency. What happens to the wavelength?


A single wind turbine has a maximum power output of 2 000 000 W. The wind turbine operated continuously at maximum power for 6 hours. Calculate the energy output in kilowatt-hours of the wind turbine.


State the life cycle of a star about the same size of our sun


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences