Question

A person is trying to judge whether a picture (mass = 1.05 kg) is properly positioned by temporarily pressing it against a wall. The pressing force is perpendicular to the wall. The coefficient of static friction between the picture and the wall is 0.720. What is the minimum amount of pressing force that must be used?

Answer 1

Answer:

the minimum amount of pressing force P will be 14.29 N

Explanation:

the friction force Fr will be

Fr = μ*N

where μ= coefficient of static friction , N= force normal to the plane

then N=P (force applied by the person)

from Newton's first law

net force = F = 0

Fr - weight = 0

μ*P - m*g =0

P = m*g/μ = 1.05 kg*9.8 m/s² / 0.720 = 14.29 N

P = 14.29 N