Velocity –time graph for a Body of mass $$10kg$$ is shown in figure. Work done on the Body in first two seconds of the motion is

Question

Velocity –time graph for a Body of mass $$10kg$$ is shown in figure.  Work done on the Body in first two seconds of the motion is

Infinity Learn · Accepted Answer

given  m $$=$$ $$10kg$$      t $$=$$ $$2$$ $$sec$$ work done by the body against retardation force $$=decrease$$ in kinetic energy of the body.   u   $$=$$   $$50m/s$$  at  t   $$=$$   $$0$$ $$sec$$.   ∴    a   $$=$$    ΔvΔt   $$=$$    $$50$$−$$00$$−$$10$$  $$=$$   −$$5$$ $$m/s2$$     ∴     speed of the Body at  t  $$=$$  $$2$$ $$sec$$  is    v  $$=$$   $$u+at$$   ⇒   v  $$=$$  $$50+($$−$$5)$$ $$2$$                            ⇒   v  $$=$$  $$40$$ $$m/s$$    ∴     using work –Energy  theory ,   W  $$=$$  Δ K.E         ⇒    W  $$=$$   $$12$$ $$mv2$$  −$$12mu2$$     ⇒    W  $$=$$   $$12$$  $$10$$×$$402$$ −$$12$$ $$10$$×$$502$$  $$=$$   −$$4500J$$

Velocity –time graph for a Body of mass 10kg is shown in figure. Work done on the Body in first two seconds of the motion is

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