Question

a forcece of 8n is applied on a body of mass 2k at rest for 10 sec and its kinetic energy

Answer 1

I think You ask the kinetic energy
so as we know F=ma
8=2a so value of a = 4m/s²
now, V = U + at
V = 0 + 4x10. (U =0 as body is in rest)
so K.E = 1/2mv²
=1/2x2x40x40
1600J

Answer 2

K.E = 1/2 ×Mass× (Velocity)^2



We have M=2 kg, F=8 Newton T= 10Sec

Here we find there is no relation of Force and time with Kinetic energy .


But we have to find velocity of the body so they can be used to find it.

we know

v= u+at 【here v= final velocity ,u= initial V, a= acceleration , t = time】

Where is the value of Acceleration .

F=ma. ( Force = Mass × Acceleration)

a=F/m= 8/2= 4 m/Sec^2

Now putting the value a in Velocity acceleration relation equation

(The velocity of the body was zero before force applied on it)

V= 0+ 4×10

V=40 m/sec


Now

KE = 1/2 × 2× 40×40= 1600 Joule