1.A block is pulled along a rough horizontal surface by a horizontal string.?

Question

If the string pulls the block at a steady speed and does work of 100 J in moving the block of distance of 5 m, find the tension in the string.

2. How to find more information on Materials Selection Chart and Materials in the Real World.

Answer 1

Figure the free space vector diagram  

You Need:

            

            Materials of contacting surfaces

            Friction coefficient for each

             Force of Friction

             Angle of pull h respect with horzontal

             Mass of cart

Answer 2

work = force * distance

100J = T * 5m

T = 20N

Answer 3

Your working equation is

Work = Force * Distance

Force = net force acting on the block

and if you draw a free body diagram, the net force

F = T - f

where

T =  tension in the string

f = frictional force acting against the block (since block is on a rough horizontal surface)

By definition,

f = (mu) * mg

where

mu = coefficient of friction

m = mass of the block

g = acceleration due to gravity = 9.8 m/sec^2 (constant)

Therefore,

f = (mu)(m)9.8 = 9.8(mu)(m)

Hence,

100 = [T - 9.8(mu)(m)](5)

T = 100/5 + 9.8(mu)(m)

T = 20 + 9.8(mu)(m)

To determine the actual value of T, two factors need to be known, i.e., the coefficient of friction (mu) and the mass of the block.