Question

Youre travelling down the road in a car with a total mass(including passengers) of 2.24 X 10^3
a)What is the change in kinetic energy of the car if you slow down from 80km/h to 70km/h(reducing your speed by 10km/h)
B)what is the change in kinetic energy of the car if you slow down from 10km/h to rest(still reducing your speed by 10km/h?
C)what form of energy does the energy lost in parts (a) and (b) turn into?

Answer 1

K.E. is proportional to the square of the velocity
this means that the energy change from 80 kph to 70 kph is greater than the change from 10 kph to zero

use (1/2 m v^2) to find the energies

the lost energy (from braking) is usually frictional (heat)