Answer to Question #265256 in Mechanics | Relativity for marie

Question

A) How much work is done in lifting a 30 kg box from a point A on the

ground to a point B on a platform 1.5 m directly above A? 

B) Show that the same amount of work would be done if the box were

carried from ground level by sliding the box along a smooth 3.0 m long plank whose one end rests on the ground away from A and the other end rests on point B. 

Answer 1

A)

$A_1=mgh=450~J,$

B)

$A_2=mgl\cos60°=450~J.$