A student slides her 80.0-kg desk across the level floor of her dormitory room a distance 3.50 m at constant speed. If the coefficient of kinetic friction between the desk and the floor is 0.400, how much work did she do

1098.65 J

Explanation:

he desk moves at constant speed, this means that its acceleration is zero, so for Newton's second law the resultant of the forces acting on the desk is zero.

There are only two forces acting on the desk: the force of the student pushing it (F) and the frictional force Ff, acting in the opposite direction, so Netwon's second law becomes

the frictional force is

where  is the coefficient of kinetic friction, m=80.0 kg is the desk mass and g is the gravitational acceleration. From this equation, we find the intensity of the force:

finally, the work done by the student is the force times the distance across which the desk has been moved:

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force