The block moves up an incline with constant speed. What is the total work Wtotal done on the block by all forces as the block moves a distance L = 4.00 m up the incline? Include only the work done after the block has started moving at constant speed, not the work needed to start the block moving from rest.

zero

Explanation:

Since the work on the block is the sum of the works done by every force acting on the block:

Wtotal = Wk + Wn + Wg

Wk ; work done by the friction force, Fk

Wn: work done by the normal force, Fn

Wg: work done by the gravity force, Fg

Since, by definition of work:

Wk = Fk*L*cos(180°) = - Fk*L

Wn = Fn*L*cos(90°) ) = 0

Wg = Fg*L*cos(90-∅) = Fg*L*sin(∅)

Wtotal = - Fk*L + 0 + Fg*L*sin(∅) (1)

Since the block moves to constant velocity, by 2° Newton's law: the sum of all forces are zero.

Using diagram of all forces, is posible demostrate:

Fk = Fg*sin(∅)

Reeplacing in the (1) expression:

Wtotal = 0

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.