A quarterback of mass 85 kg is running at 10 m/s. Also, a tackle of mass 100 kg is running at 9 m/s.
A) The tackle has the greater kinetic energy.
B) The quarterback and the tackle have equal kinetic energies.
C) The quarterback has the greater kinetic energy.

Question

Quizplus · Accepted Answer

The kinetic energy of an object is given by the formula KE = 0.5*m*v^2, where m is the mass of the object and v is its velocity. 
Plugging in the values given for the quarterback: 
KE = 0.5 * 85 kg * (10 m/s)^2 = 4,250 J 
Plugging in the values given for the tackle: 
KE = 0.5 * 100 kg * (9 m/s)^2 = 4,050 J 
Since the velocity of the quarterback is higher than the tackle, the quarterback has a greater kinetic energy. Therefore, the answer is choice C.

A Quarterback of Mass 85 Kg Is Running at 10