Question

Which of the following has the largest kinetic energy?

A. a 10kg dog running down the street at 30mph
B. a tightrope walker slowly crossing niagara falls
C. a 0.02kg bullet moving down the barrel at 800mph
D. a semi truck parked in a parking lot

Answer 1

Option C,

Reason

Kinetic energy is proportional to the square of velocity. Thus the higher the velocity the higher will be the kinetic energy

K.E. dog = 1/2 x 10 x (0.44704 x 30)^2 m/s = 899.14 J

K.E. bullet = 1/2 x 0.02 x (0.44704 x 8000)^2 m/s = 127,878 J