Question

A ball of mass 2kg and another of mass 4kg are dropped together from a 60feet tall building. After a fall of 30 feet each towards earth, their respective kinetic energies will be in the ration of ___________

(a) √2:1

(b) 1:4

(c) 1:2

(d) 1:√2

I got this question in quiz.

Asked question is from Forces and Inertia topic in portion Gravitation of Engineering Physics I

Answer 1

The correct choice is (c) 1:2

To explain: Both balls attain same velocity v after falling through 30 feet height.

E1/E2 = (1/2 m1 (v1)^2)/(1/2 m2 (v2)^2) = (2v^2)/(4v^2)=1/2=1:2.