Question

Write expression for Kinetic Energy.A force of 12N acts on an

object of mass of 4kg in the state of rest for 3s. Calculate the kinetic energy acquired by the

object.​

Answer 1

Explanation:

Kinetic energy is a property of a moving object or particle and depends not only on its motion but also on its mass. The kind of motion may be translation (or motion along a path from one place to another), rotation about an axis, vibration, or any combination of motions

ke =1/2 mv^2. or. k.e = (force)^2 ×(time)^2 /mass

in ur case

F=12 N

M=4kg

T=3 s

so

ke. = (12)^2 ×(3)^2/4

=324 j ans

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Answer 2

Answer:

We know that ,

          $a(acceleration ) = \frac{v-u}{t} \\\\u = 0 \ , a = \frac{v}{t}$------------------(i)

Force , F = 12N = m*a

Here , mass , m = 4 Kg

          => F = ma

          => 12 = 4 * a

          => a = 3 m/s²

By putting the value of a in equation (i) ,

          => 3 * t = v

          => v = 9 m/s                                { t = 3s given }

Now ,

         $KE = \frac{1}{2} mv^{2} \\\\KE = \frac{1}{2} * 4 * 3^{2}\\\\KE = 2 * 9\\\\KE = 18 J \ (Ans.)$

         Hope it helps

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Explanation: