A spherical body of mass 2 kg starting from rest acquires a kinetic energy of 10000 J at the end of $\mathrm{5^{th}}$ second. The force acted on the body is ________ N.
Answer (integer)
40
Solution
Let the force be $F$ so acceleration $a=\frac{F}{m}$
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So displacement $S=\frac{1}{2} a t^{2}=\frac{F t^{2}}{2 m}$
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So work done $W=F . S=\frac{F^{2} t^{2}}{2 m}$
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From work energy Theorem
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$\Delta K E=W$
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$W=\frac{F^{2} t^{2}}{2 m}=10000$
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$F=\sqrt{\frac{10000 \times 2 \times 2}{5^{2}}}$
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$F=40 \mathrm{~N}$
About this question
Subject: Physics · Chapter: Work, Energy and Power · Topic: Work Done by a Force
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