How much work would it take to horizontally accelerate an object with a mass of #2"kg"# to #9"m/s"# on a surface with a kinetic friction coefficient of #3#?
It can be anything greater than
The change in kinetic energy,
It will be "81"J"# no matter how you push the object, so the work done will be at least that.
The work done against friction on the other hand, can vary from infinitesimally small to infinitely big. Let's consider the 2 extreme cases intuitively.
The fundamental reason is that the energy lost is the product of the
In the case where a huge force is applied, the objects reaches the final speed of
On the other end of the spectrum, consider applying a constant force of