How Much Energy Is Needed to Drag a Block Over a Distance?

[indie452]

Homework Statement

whats the energy required to drag a block a distance L

Homework Equations

coefficiant of friction between block and floor = $$\mu$$
density of block = p

force*distance = change in kinetic energy

The Attempt at a Solution

friction acting against movement Fr = $$\mu$$mg m = mass of block

force in direction of movement F = ma

resultant force = F - Fr = m(a-$$\mu$$g)

resultant force*L = energy = m(a-$$\mu$$g)L

i don't think the last step is right though as I am not sure sure that the assumption made that energy required is the same as the change in KE is correct...

help or guidance appreciated

 

[PhanthomJay]

Although not stated as such, I think you are looking for the energy (work) required by a person or machine to just overcome friction and move the block at constant speed (no acceleration).