Answer to Question #116744 in Mechanics | Relativity for maham

Question

I drag a mass m=21 kg in a straight line, along a horizontal surface, a distance D= 23m .I drag it at constant speed v=0.90m/s in a straight line using a horizontal force.the coefficient of static friction is 1.2 and coefficient of kinetic friction is 1.1.How much work do I do in joules?

Answer 1

As the object is in motion hence kinetic friction will take place

kinetic friction = $\mu_k\times N=1.1\times21\times10$ =$231 N$

lets apply work energy theorem

$\sum W=\Delta K$

$W_N+W_f+W_{mg}+W_F=\Delta K$

$0-(231\times23)+0+W_F=\frac12\times21\times0.9^2$

$W_F=5321.5 J$