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Q.
How much work must be done by a force on 50 kg body in order to accelerate it from rest to 20 $ms^{-1}$ in 10 s
Work, Energy and Power
Solution:
Final velocity v = u + at
$\therefore $ $20 =0 +a \times 10$ or
$20 =a \times 10$ or
$a=2 ms^{-2}$ now
$s=ut+\frac{1}{2}at^2$
or $s=0+\frac{1}{2}\times 10 \times 10 \times $ or s=100m
$\therefore $ work done W = F $\times$ s or W = ma $\times$ s
$\therefore $ $W=50 \times 2 \times 100 \,or\,W =10000$
$=10^4J$