13.1 - Oscillations

Question 1

There are many things around us which oscillate, what does this mean

Answer 1

This means they undertake continuously repeated movements. For example, a child’s swing goes backwards and forwards through the same positions over and over again. If left to swing freely, it’s will always take the same time to complete one full swing. This would be known as its time period, T. It follows a system of movements known as simple harmonic motion

Question 2

What does SHM stand for

Answer 2

Simple harmonic motion

Question 3

What happens when a system is moving in SHM

Answer 3

A force, known as the restoring force, F, is trying to return the object to its equilibrium position, and this force is proportional to the distance, x, from that equilibrium position.

F = -kx

Question 4

Tell me about the equation for calculating restoring force

Answer 4

F = -kx

Where x is the distance from equilibrium position.
K is a constant dependent on the oscillating system in question.
The negative sign in the equation shows us that the acceleration will always be towards the centre of oscillation.

Question 5

You will notice that the SHM definition is the same equation as in…

Answer 5

Hookes law, and the oscillation of a mass attached to a spring is an example of SHM.

Question 6

How can we find the equation for the period of the oscillations of a mass, m, subject to a Hookes law restoring force

Answer 6

T = 2pi x square root (m/k)

Question 7

What is the period for a pendulum given by

Answer 7

Legend has it that Galileo was just 17 when, watching a hanging lantern in the cathedral in Pisa, he observed that a pendulums time period is independent of the size of the oscillations, in fact the period for the pendulum is given by:

T = 2pi x square root (l/g)

Therefore, the period is only dependent on the length, l, of the pendulum string, and the strength of gravity on the planet which It has been set up.