Work Energy And Power Ques 15
15. An object of mass $500$ $ g$, initially at rest, is acted upon by a variable force whose Xcomponent varies with $X$ in the manner shown. The velocities of the object at the points $X=8$ $m$ and $X=12 $ $m$, would have the respective values of (nearly)
[NEET Odisha 2019]
(a) $18 $ $m / s$ and $20.6 $ $m / s$
(b) $18 $ $m / s$ and $24.4 $ $m / s$
(c) $23 $ $m / s$ and $24.4 $ $m / s$
(d) $23 $ $m / s$ and $20.6 $ $m / s$
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Answer:
Correct Answer: 15.(d)
Solution:
- (d) Using work-energy theorem, $\Delta K=$ work $=$ area under $F-x$ graph
From $x=0$ to $x=8$ $ m$
$\frac{1}{2} m v^{2}=100+30$
$\therefore v=\sqrt{520}=23 $ $m / s$
From $x=0$ to $x=12$ $ m$
$\frac{1}{2} m v^{2}=100+30 -47.5+20$
$\therefore v=\sqrt{410}=20.6 $ $m / s$
BETA
