KCET · Physics · Semiconductors
The kinetic energy of a body of mass \( 4 \mathrm{~kg} \) and momentum \( 6 \mathrm{Ns} \) will be
- A \( 2.5 \mathrm{~J} \)
- B \( 3.5 \mathrm{~J} \)
- C \( 4.5 \mathrm{~J} \)
- D \( 5.5 \mathrm{~J} \)
Answer & Solution
Correct Answer
(C) \( 4.5 \mathrm{~J} \)
Step-by-step Solution
Detailed explanation
Given, mass, \( m=4 \mathrm{~kg} ; \) momentum, \( m v=6 \mathrm{~N} \mathrm{~s} \)
Therefore, kinetic energy
\( =\frac{1}{2} m v^{2}=\frac{1}{2} \frac{(m v)^{2}}{m}=\frac{6 \times 6}{2 \times 4}=\frac{36}{8}=4.5 \mathrm{~J} \)
Thus, kinetic energy of body \( =4.5 \mathrm{~J} \)
Therefore, kinetic energy
\( =\frac{1}{2} m v^{2}=\frac{1}{2} \frac{(m v)^{2}}{m}=\frac{6 \times 6}{2 \times 4}=\frac{36}{8}=4.5 \mathrm{~J} \)
Thus, kinetic energy of body \( =4.5 \mathrm{~J} \)
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