flywheel experiment

7/24/2019 Flywheel Experiment

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Introduction

A flywheel is a large disc with a certain mass and dimension depending on the purpose that

rotates freely and stores kinetic energy. The flywheel is essentially a mechanical battery as it

stores the energy and then discharges. A flywheel with greater mass and dimensions will

have bigger power storage.

An example of a flywheel is attached to the crankshaft in a car engine which stores the

energy of the firing pistons and then discharges to allow for a constant smooth power output.

The use of the fly wheel cuts down on the vibrations of the engine. A simpler use of a

flywheel is in a toy car where a large flywheel is connected to the driven wheels and when

the car is pushed forward the flywheel stores the initial acceleration and then uses this

energy to propel the car after it is released. Another example of the use of a flywheel is in

uninterrupted power supply systems where the flywheel is used instead of a battery.

Advantages of using the fly wheel in this situation would cut down on maintenance and have

less impact on the environment as it is made of harmless materials. The flywheel does have

disadvantages as it can be very expensive and when it overloads it can shatter

The main objective of this experiment is to find the relationship between time and

displacement.

Theory

Considering the forces acting on the falling mass (M and !ewton"s second law of motion#

$. Mg−T = Ma

%or the flywheel the tension# T provides an acceleration tor&ue for the flywheel#

'. Tr= I α

here I =

1

2 M f R

2

) is the polar moment of inertia for the fly wheel and * is the angular acceleration.

Assuming that the string does not stretch then

+. a=α r

,ubstitute e&uations ' and + into $ to obtain-

Mg− Ia

r2= Ma



.

a=g

1+ I

M r2

Assuming the acceleration a is constant from release# time taken can be predicted for aspecific fall s. !ow using an e&uation of motion and rearranging it when u/0.

s=ut +1

2a t

2

s=1

2a t

2

1. t

2

=

2s

a

!ow the e&uation is rearranged for t 2

we can sub in e&uation to derive an e&uation t.

2. t

2=2 s

g (1+

I

M r2)

Apparatus

%igure $

All the dimensions in figure $ are in mm



)n this experiment a flywheel with diameter +00mm and thickness of 3mm was used. And a

weight of $! was attached to the shaft of dimensions $$+mm length and +2mm diameter.

The wall at the back of the flywheel had lines spaced at intervals of 0.'m so that readings

could be taken at each. A stopwatch was also used in this experiment to take the time taken

for the mass to fall.

Procedure

The mass of $! attached to the shaft and flywheel was aligned to the 0.$ m marking

on the wall this was difficult since the weight wasn"t close to the wall so this could

have caused inaccurate readings.

)t was then dropped and allowed to accelerate from 0 m to 0.'m and the readings

from stopwatches were taken.

This was repeated for each interval of 0.'m up to 4m

Results

5isplacement

(m

6esults (s Mean of

results

7ncertaintie

s (8s

0 0 0 0 0 0 0

0.' 3.0 3.13 3.3 3.+ 3.1 0.131

0. $$.0 $$.$' $0.9 $0.90 $$.00 0.011

0.2 $'.43 $'.9 $'.4 $'.9$ $'.49 0.0'1

0.4 $1.'1 $1.+ $1.$4 $1.02 $1.'$ 0.030Table 1

Table one shows the results from the experiment the uncertainties where

calculated by,

Random uncertainty =maximumreading−minimumreading

number of readings

Displaceme

nt (m)

0 0.2 0. 0.! 0."

Results for

t 2

(s)

Table 2

Table 2 shows the theoretical results for the #ywheel. They were calculated usin$

the method below

t 2=

2 s

g (1+

I

M r2)

1+0.46

❑

¿2 (0.2)9.81

¿

flywheel experiment

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