Question

Lucy and her bike together have a mass of 120 kg. She slows down from 4. 5 m/s to 3. 5 m/s. How much kinetic energy does she lose?.

Answer 1

The answer is - 480 kj

Step-by-step explanation:

kinetic energy before: K1 = 1/2 *m*U1^2=} K1= 1/2*120*4.5^2=} K1= 60*4.5*4.5=} K1= 1,215 kj

kinetic energy after : K2=1/2 *m*U2^2=} K2= 1/2*120*3.5*3.5=} K2= 735 kj

if you want to find the kinetic energy that the mass has lost you need to do : K2-K1= 735-1.215= - 480 kj