# 11: Modelling Oscillations Flashcards

Define simple harmonic motion

An oscillation in which the restoring force on an object, and hence the acceleration of the object, is directly proportional to its displacement from the midpoint, and is directed towards the midpoint

What is the type of potential energy that is providing the restoring force for pendulums?

Gravitational

What is the type of potential energy that is providing the restoring force for springs?

Elastic strain energy

Describe the different energies as the object moves towards the midpoint and away again

(Simple harmonic motion)

As the object moves towards the midpoint, the restoring force does work on the object and so transfers some PE to KE

When the object is moving away from the midpoint, all that KE is transferred back to PE again.

What is the potential energy and the kinetic energy, when the object is at the midpoint?

(Simple harmonic motion)

PE = 0 KE = maxiumum

What is the potential energy and the kinetic energy, when the object is at the maximum displacement?

(Simple harmonic motion)

KE = 0 PE = maximum

Describe the sum of the potential and kinetic energy of an object in simple harmonic motion

The mechanical energy stays constant

Mechanical energy = KE + PE

What is the cycle of an oscillation?

From maximum positive displacement to maximum negative displacement and back again

Describe the relationship between frequency, period, and amplitude and simple harmonic motion

The frequency and period are independent of the amplitude

Describe the set up for the experiment of a mass on a spring in simple harmonic motion

A mass on the end of the spring connected to a string, held in a clamp and clamp stand on the edge of a workbench. Underneath the mass is a position sensor, attached to a computer

Describe the experiment of a mass on the end of the spring

SHM

Pull the masses down a set amount – this displacement will be your initial amplitude. Let the masses go

The masses will now oscillate with simple harmonic motion.

The position sensor will measure the displacement of the mass over time

Create a displacement time graph. Read off the time period

Experiment looking at a mass on the end of a spring, (SHM):

How can you investigate how mass changes the experiment?

Add extra masses to the spring

Don’t stretch the spring past its limit of proportionality

Experiment looking at a mass on the end of a spring, (SHM):

How can you investigate how the spring constant changes the experiment?

Use different springs, or combinations of springs.

Experiment looking at a mass on the end of a spring, (SHM):

How can you investigate how amplitude changes the experiment?

Pull the mass down by different amounts. Be careful about how far you stretch the spring, don’t stretch it past the limit of proportionality

Describe the set up of the investigation of a simple pendulum

Attach a piece of card and a protractor to a clamp on a clampstand. Attach a string with a bob on the end to the clamp. Put a reference mark in the equilibrium position

Measure the mass of the bob and use a ruler to find the length of the string