Question

A man cleaning his apartment pulls a vacuum with a force of 50N at an angle of 30°. A friction force of 40N retards the motion and the vacuum cleaner is pulled a horizontal distance of 3m. Calculate the net work done by the 50N pull

Answer 1

Solution.

$F_p=50N;$

$\varTheta=30^o;$

$F_f=40N;$

$d=3m;$

$W-?;$

$W=Fcos\varTheta d;$

Traction force work: $W_p=50N\sdot0.866\sdot3m=130J;$

Work of friction force (angle is equal to 180^o): $W_f=40N\sdot(-1)\sdot3m=-120J;$

Net work:

$W=W_p+W_f;$

$W=130J-120J=10J;$

Answer: $W=10J.$