Question

A block of mass 4.0 kg rests on a horizontal surface where the coefficient of kinetic friction between the two is 0.20. A string attached to the block is pulled horizontally, resulting in a 3.0-m/s2 acceleration by the block. Find the tension in the string. (g = 9.80 m/s2)

Answer 1

Solution:-

Given in question :-

mass of block = 4 kg
coefficient of kinetic friction = 0.2
Acceleration of block = 3.0
g = 9.80

Asked in question :- Tension in string

Now,

Normal force applied by surface on block = (mass of block * g) = 4.0 * 9.8 = 39.2 N
Kinetic friction = f = (coefficient of kinetic friction) * (Normal force) = 0.2 * 39.2 = 7.84 N

let's assume tension = T

Then, Friction will oppose the movement of block and Tension will try to move the block so these two forces will have opposite direction.

Now, Using newton's second law of motion in Horizontal direction :-





So, The tension in string is 19.84 N