Question

Two spherical balls of the same radius but of different masses, are dropped at the same time from the top of a tower $19.6m$ high. When they are $1.6m$ above the ground, the balls will possess the same

• A. K.E.
• B. P.E.
• C. Momentum
• D. Total energy

Answer 1

The correct option is D Total energy

$a_A=g$ initial energy of $A=M_{A}g\left(19.6\right)$

$a_B=g$ initial energy of $B=M_{B}g\left(19.6\right)$

Find energy of $A=\frac{1}{2}{M}_A{V}_A^2$

Find energy of $B=\frac{1}{2}{M}_B{V}_B^2$

$V_A=\sqrt{2gh}{V}_B=\sqrt{2gh}$

Find energy of $A=\frac{1}{2}{M}_A.2gh\Rightarrow M_{A}g\left(19.6\right)B=\frac{1}{2}{M}_B.2g\Rightarrow M_{B}g\left(19.6\right)$

So the ball $A$ and $B$ will posses same total energy.