An object with a mass of 5kg is pushed along a linear path with a kinetic friction coefficient of uk(x)=ex+x. How much work would it take to move the object over #x in [1, 2], where x is in meters?

2 Answers
May 7, 2017

283.53J

Explanation:

First we will write the information provided
μk=ex+x
M=5Kg

we know that the work done by us to the 5 kg mass is
W=Fappliedds

but in this case there is friction is involved which can be included in the equation by ,

W=(Fappliedfk)dS

here we need to move the block without acceleration so the applied force must be equal to the kinetic friction .
Fapplied=fk

similarly the work done will also be the same in both the cases so the work done by the frictional force is given by .

W=fkdx=μkNdx=21(ex+x)mgdx=283.53J

May 7, 2017

The work is =302.3J

Explanation:

The work done is

W=Fd

The frictional force is

Fr=μkN

N=mg

Fr=μkmg

=5(ex+x)g

The work done is

W=5g21(ex+x)dx

=5g[ex+x22]21

=5g((e2+2)(e+12)))

=5g(9.393.22)

=5g6.17

=302.3J