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Question

Derive the formula for kinetic energy (½mv²). (NCERT Class 9 – Important)

Answer: Work done W=Fs. Using F=ma and v²−u²=2as ⇒ a=(v²−u²)/2s. So W=ma s = m(v²−u²)/2. If u=0, W=½mv² = kinetic energy.

Question

Derive the formula for kinetic energy (½mv²). (NCERT Class 9 – Important)

Answer: Work done W=Fs. Using F=ma and v²−u²=2as ⇒ a=(v²−u²)/2s. So W=ma s = m(v²−u²)/2. If u=0, W=½mv² = kinetic energy.