JEE Mains · Physics · STD 11 - Work,energy,power and collision
- JEE Mains 2024
- Hard
- MCQ
If a rubber ball falls from a height \(h\) and rebounds upto the height of \(h / 2\). The percentage loss of total energy of the initial system as well as velocity ball before it strikes the ground, respectively, are _______.
Pick an option to check your answer.
Answer & Solution
Correct Answer
(D) \(50 \%, \sqrt{2 \mathrm{gh}}\)
Step-by-step Solution
Detailed explanation
\(\text { Velocity just before collision }=\sqrt{2 \mathrm{gh}}\)
\(\text { Velocity just after collision }=\sqrt{2 \mathrm{~g}\left(\frac{\mathrm{h}}{2}\right)}\)
\(\therefore \Delta \mathrm{KE}=\frac{1}{2} \mathrm{~m}(2 \mathrm{gh})-\frac{1}{2} \mathrm{mgh}\)
\(=\frac{1}{2} \mathrm{mgh}\)
\(\therefore \% \text { loss in energy }\)
\(=\frac{\Delta \mathrm{KE}}{\mathrm{KE}_{\mathrm{i}}} \times 100=\frac{\frac{1}{2} \mathrm{mgh}}{\frac{1}{2} \mathrm{mg} 2 \mathrm{~h}} \times 100=50 \%\)
Hence option \((4)\)
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