Question

A lead ball of mass 2 kg moving with a velocity of $1.5m{s}^{-1}$ hits against a ball of mass 3 kg at rest. If the second ball moves with a velocity of $1m{s}^{-1}$ after the impact in the original direction of motion of the first ball, the loss of K.E. due to impact is

• A. 0.033 J
• B. 0.75 J
• C. 1.5 J
• D. 2,25 J

Answer 1

The correct option is B 0.75 J

From COLM
$2\times 1.5+3\times 0=2V_1+3\times 1$
$\Rightarrow V_1=0$
$K{E}_i=\frac{1}{2}\times 2\times (1.5{)}^2=2.25J$
$K{E}_f=\frac{1}{2}\times 3\times 1^2=1.5J$
$\Delta KE=0.75J$