Question

An 18 kg bicycle carrying a 62 kg girl is traveling at a speed of 7 m/s. What is the kinetic energy of the girl and bicycle?

Answer 1

Ke=1/2 mv^2
(.5)(80)(7^2)=1960 joules

Answer 2

To get the answer we have to substitute total mass and velocity to the formula
E=$\frac{1}{2} mv^2$, so
E=$\frac{1}{2} (18+62)*7^2= \frac{1}{2}*80*49=40*49= 1960J$ - its the answer