Question

A body of mass 5 kg rests on a rough horizontal surface of coefficient of friction 0.2. The body is pulled through a distance of 10 m by a horizontal force of 25 N. The kinetic energy acquired by it is :

• A. 200 J
• B. 150 J
• C. 100 J
• D. 50 J

Answer 1

The correct option is B 150 J

Normal Reaction on the body$=N=mg=5\times 10=50N$

Horizontal force acting on the body$F_H=25N$

Frictional force acting on the body $F_f=\mu N=0.2\times 50=10N$

Net force acting on the body $F_{net}=F_H-F_f=25-10=15N$

By work-energy theorem,

KE acquired by the body= Work done on the body$=F_{net}.s=15\times 10=150J$

Hence, correct answer is option $B$