Question

At what speed does a 1400 compact car have the same kinetic energy as a 20000 truck going 25 ?
Express your answer using two significant figures.

Answer 1

K=1400*V^2/2
K=20000*25^2/2. => 1400*V^2/2=20000*25^2/2 <=> 1400*V^2=20000*25^2
14*V^2=200*225
v^2=100*225/7
v=250/7^(1/2)

Answer: 250*7^(1/2)/7