# Investigating factors that affect the swing of a pendulum

During this investigation I will isolate and investigate some of the factors that affect the amount of swings that a pendulum can complete in a given amount of time.

Introduction:

A Pendulum comprises of a ‘rod’ (a length of material, it can be flexible or rigid) and a ‘bob’ (a weight which is attached to the rod), these then oscilate, by altering the properties of these two factors it is possible to achieve any rate of ‘regular swing’, once the desired rate is achieved, a pendulum can be used to govern any types of machinery.

Plan:

I have isolated the key factors that will affect the swing of the pendulum as: The angle of release

The length of the pendulum arm

The weight of the bob

In this experiment I will concentrate on the length of the pendulum rod, as I feel this will have the most affect on the results. I will be keeping the ‘mass’ and the ‘angle of release’ the same throughout the experiment

From this I will predict that a shorter rod will result in the pendulum completing more swings in a given time, I have predicted this because:

If a car was to negotiate a 90 degrees corner,

the fastest route would be one where it could

turn very quickly, e.g.

A car negotiating this corner may cover something in the range of 5 – 10m, if it could take the corner in a ‘tighter’ fashion (simulating a smaller rod) The effect would be that the car would cover a shorter distance, resulting in the corner taking a shorter time to negotiate.

The apparatus I will use for this experiment will be:

A stand

A boss

A clamp

String

10g slotted mass’s

A stop clock

Diagram:

Once I have set up the apparatus, I will hold the bob in my hand, and release it from a 45 degrees angles, then I will count how many times the pendulum swings back and forth, thus completing one swing.

Obtaining Evidence:

To make the results accurate I repeated each experiment 3 times, and then averaged the 3 results to give an accurate and fair measurement.

Mass of bob

Length of ‘rod’

Time

Repeat 1

Repeat 2

Repeat 3

Average number of swings

50g

5cm

30 secs.

42

41

42

41.7

50g

10cm

30 secs.

37

37

37

37

50g

15cm

30 secs.

33

32

32

32.3

50g

20cm

30 secs.

29

29

30

29.3

50g

25cm

30 secs.

27

28

27

27.3

50g

30cm

30 secs.

25

25

25

25

50g

35cm

30 secs.

23

23

23

23

50g

40cm

30 secs.

22

22

21

21.7

50g

45cm

30 secs.

21

20

21

20.3

50g

50cm

30 secs.

20

19

19

19.3

From this graph you can see that there is a clear connection between the length of the rod and the number of swings, in that the shorter the rod, the more swings the pendulum can complete. This supports my prediction because, as the rod was made longer, the number of swings completed in 30 seconds decreased.

Evaluation:

I feel that the results that were gathered were accurate and fair as the repeats gave similar results, and set a clear trend.

I feel the method was appropriate but that it could have been made better by using some kind of automated counting device such a