Question

A uniform force of 5N starts acting opposite to the direction of motion on a body of mass 8 kg moving with
an initial speed of 13 m/s for a distance of 20 m. Then the final K.E. of the body is (neglect friction) :
(A) 376 J (B) 476 J (C) 576 J (D) 676 J

Answer 1

As the given data Suggests,

u= 13 m/s

S= 20m

M= 8kg

What we need is Final Kinetic Energy and the velocity provided is ‘initial'

So, We can obtain Final velocity with the help of acceleration and acceleration by Force and Mass

--> F=ma

a= F/M

a= 5/8 = 0.6 m/s^2

By equation of motion;

V^2 = u^2 + 2aS

--> v^2 = 169+ 2 * (-0.6) * 20m

v^2 = 169 -24

v^2= 145

Then, The final K.E. = 1/2 m*v^2

--> K.E. =580 J ≈576 J....

Thats my Part....

Hope it simplifies

Thanks!!