A parcel of mass 10 kg rests on a lorry. When the lorry accelerates at 1.5 m/s^2, the parcel is just about to slide backwards. What is the co-efficient of friction between the parcel and the lorry?

The coefficient of static friction, μ = 0.153

Explanation:

Given data,

The mass of the parcel, m = 20 kg

The acceleration of the lorry, a = 1.5 m/s²

The normal force acting on the parcel,

f = m x g

= 20 x 9.8

= 196 N

The static frictional force acting on the lorry,

F = 20 x 1.5

= 30 N

The coefficient of static is

μ = F / f

= 30 / 196

= 0.153

Hence, the coefficient of static friction, μ = 0.153