A block has two strings attached to it on opposite ends. One string has a force of 5 N, the other string a force of 15 N. The block is accelerating at 1 m/s2

on a horizontal

surface.
A) What is the mass of the block if the friction force is 3 N?

B) What is the coefficient of friction?

A) 7kg

B) 0.044

Explanation:

a) Accordimg to Newton's second law

\sum F = ma

Fm - Ff = ma

Fm is moving force =15-5 = 10N

Ff is fictional force = 3N

m is the mass = ?

a Is the acceleration = 1m/s²

Substitute

10-3 = 1m

7 = m

Hence the mass of the body is 7kg

b) coefficient of friction is expressed as;

n = Ff/R

R is the reaction = mg

n =Ff/mg

Substitute

n = 3/7(9.8)

n = 3/68.6

n = 0.044

Hence the coefficient of friction is 0.044