Question

Block $A$ with a kinetic energy of $500\text{J}$ collides with another block $B$ of mass $10\text{kg}$ initially kept at rest. Assuming that the collision is perfectly elastic, what is the final speed of the block $B$?

• A. $100\text{m/s}$
• B. $0\text{m/s}$
• C. $10\text{m/s}$
• D. $5\text{m/s}$

Answer 1

The correct option is C $10\text{m/s}$

Since the collision is perfectly elastic,
kinetic energy will be conserved and all the kinetic energy of the block $A$ is transferred to the block $B$.

Hence,
$K{E}_A=K{E}_B$
$500=\frac{1}{2}{m}_b{v}_B^2\Rightarrow 500=\frac{1}{2}\times 10\times v_B^2$
$\Rightarrow v_B^2=100$
$\Rightarrow v_B=10\text{m/s}$
Hence the correct option is (c).