Question

A man on the bank of the river pulls a boat on water with the rope that makes 30 degrees, with the bank. He exerts a force of 60lbs. What is the useful component of this force?why is it called useful?

Answer 1

As per the question

The force or pull makes an angle of $30\degree$ with the bank

Force=60lbs

The sin component of force is useful because this component is responsible

Th component=F$sin30\degree=60\times0.5=30lbs$

and the other component $Fcos30\degree=60\times0.866=51.96lbs$

Sine component is useful since this component help the man to cross the river as it acts to the perpendicular of the direction of river.