AP EAMCET · PHYSICS · Work Power Energy
A machine with efficiency \(2 / 3\) used 12 J of energy in lifting 2 kg block through certain height and it is allowed to fall through the same. The velocity while it reach the ground is
- A \(\sqrt{2} \mathrm{~ms}^{-1}\)
- B \(2 \mathrm{~ms}^{-1}\)
- C \(2 \sqrt{2} \mathrm{~ms}^{-1}\)
- D \(0.2 \mathrm{~ms}^{-1}\)
Answer & Solution
Correct Answer
(C) \(2 \sqrt{2} \mathrm{~ms}^{-1}\)
Step-by-step Solution
Detailed explanation
Potential energy of the machine, \(\begin{aligned} & \mathrm{U}=\frac{2}{3} \times 12=8 \mathrm{~J} \\ & \Rightarrow \mathrm{mgh}=8 \Rightarrow \mathrm{~h}=\frac{8}{2 \times 10}=0.4 \mathrm{~m} \end{aligned}\) By conservation of energy, Loss in PE = Gain in K.E…
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