Physics: Hooke’s Law

Tutoring physics, Hooke’s Law is perennial. The tutor begins about it.

The following is by my understanding.

Hooke’s Law is often visited in Physics 11, and applies to springs. It can be used to find a spring constant, the force involved to compress or stretch a spring to a given new length, or how much a spring will change length when subject to a force.

The main formula connected with Hooke’s Law:

F=-kx

The negative sign means the spring’s reaction force is against the force to change its length. The k symbol stands for the spring constant, given in force/length, N/m in base units. The x symbol stands for the change in length relative to rest length. F means the force in play.

Example: imagine a spring has constant 55N/m and a rest length of 40.cm. A 500.g mass is hung from it. Afterwards, what is its new length?

Solution: 500.g=0.500kg, so gravitational force on it will be mg=0.500(-9.8)=-4.9N (the negative means downward). F=-kx⇒-F/k=x⇒-(-4.9)/55=0.089m or 8.9cm.

Therefore, the spring will be stretched 8.9cm by the mass, resulting in its new length being 48.9cm after the mass is hung from it.

There is more to say about Hooke’s Law; I hope to follow up about it in coming posts:)

Source:

Heath,R.W., Macnaughton,R.R., Martindale,D.G. (1979). Fundamentals of Physics. D.C. Heath Canada Ltd.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.