Answer to Question #177443 in Classical Mechanics for Jethro Torio

Question

A box is pulled on level ground by a force of 40 N that makes 45° with the ground.

Find a) the force that tends to lift the box, and b) the force that tends to pull the box forward.

Answer 1

$\text{expand the force F into vertical and horizontal projections}$

$\vec{F}= \vec{F}*\cos\alpha+\vec{F}*\sin\alpha$

$\text{a) the force that tends to lift the box is } \vec{F}*\cos\alpha= 40*\frac{1}{\sqrt2}\approx28.3 J$

$\text{b) the force that tends to pull the box forward is}\vec{F}*\sin\alpha= 40*\frac{1}{\sqrt2}\approx28.3 J$

Answer:a) 28.3J b) 28.3J