Question

a 20 kg block is originally at rest on a horizontal surface for which the coefficient of friction is 0.6 if a horizontal force f such that it varies with time determine speed of block at 10 sec

Answer 1

The speed will be 28.8 ms^(-1 )

Explanation:

First, we have to calculate the frictional force:

F = μ mg = (0.6) (20) (10) = 120 N

Now,  

F -120/20 = dV/dt         ( comparing acceleration) on both sides  

Now, the equation of F from the graph is given below:

F = 40t    3<t<5  ( because block will move when F> 120)

F = 200  5<t<10

So by putting the value of F and solving equation (i) by integration we get

V = 28.8 ms^(-1 )