Question 345: Centre of Mass and Rotational Motion

Question

Force is applied to a body of mass $$2 \mathrm{~kg}$$ at rest on a frictionless horizontal surface as shown in the force against time $$(F-t)$$ graph. The speed of the body after 1 second is

Accepted Answer

Area under the $$\mathrm{F}-\mathrm{t}$$ graph gives change in momentum. Since the body is initially at rest, it gives the momentum of the body after 1 second.
$$\begin{aligned}
	ext { Area } & =10 	imes 0.5+20 	imes 0.5 \
& =5+10=15 \mathrm{~N}-\mathrm{s} \
	herefore \mathrm{mV} & =15 \mathrm{~N}-\mathrm{s} \
\mathrm{V} & =\frac{15}{\mathrm{~m}}=\frac{15}{3}=7.5 \mathrm{~m} / \mathrm{s}
\end{aligned}$$

Answer

7.5 m/s

Answer

12.5 m/s

Answer

10 m/s

Answer

15 m/s

Centre of Mass and Rotational Motion

Force is applied to a body of mass $2 \mathrm{~kg} at rest on a frictionless horizontal surface as shown in the force against time (F-t)$ graph. The speed of the body after 1 second is

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