Two cannonballs are dropped from a second floor physics lab at height h above the ground.Ball B has four times the mass of ball A.When the balls pass the bottom of a first floor window at height $\frac { h } { 4 }$ above the ground,the relation between their kinetic energies,K_A and K_B,is A)K_A = 4K_B. B)K_A = 2K_B. C)K_A = K_B. D)K_B = 2K_A. E)K_B = 4K_A.

Question

Quizplus · Accepted Answer

The kinetic energy of an object is given by $ K = \frac{1}{2}mv^2 $. Since both balls are dropped from rest, they have the same velocity when passing the window. Ball B has four times the mass of ball A, so its kinetic energy is four times that of ball A.

Two Cannonballs Are Dropped from a Second Floor Physics Lab h4\frac { h } { 4 }4h​

Two Cannonballs Are Dropped from a Second Floor Physics Lab $\frac { h } { 4 }$