Inertia (Experiment)

Inertia (Experiment)

Essay Question.

 

In a supermarket, firdaus help his mother to push an empty trolley to carry the things she intends to buy. After shopping, he pushes the trolley which is full to the cashier’s counter. Firdaus noticed that it is more difficult to push full trolley compared to an empty one.

                  

Based on the observation,

a) make one suitable inference,                                                                            [1 mark]

b) state one appropriate hypothesis that could be investigate                      [1 mark]

c) describe how you would design an experiment to test your hypothesis using an 
    inertia balance, G-clamp and other apparatus. In your description, clearly state the              
    following :

    i)  aim of the experiment

    ii) variables in the experiment

    iii) list of apparatus and materials

    iv) arrangement of the apparatus

    v) the procedures of the experiment, which includes the method of controlling the  
        manipulated variable and the method of measuring the responding variable.

   vi) the way you would tabulate the data

   vii) the way you would analyse the data                                                         [10 marks]

Answer :

Option 1:  Using an inertia balance

Inference : Inertia depends on mass
 

Hypothesis: The larger the mass, the bigger the inertia

Aim of the experiment: To study the effect of mass on the inertia of an object.

Variables:
Manipulated: Mass, m
Responding: Period of oscillation, T
Constant: Stiffness of the inertia balance 

Apparatus/Materials: Inertia balance, masses for the inertia balance, G-clamp, stopwatch.

Setup: 

Procedure:
1. The inertia balance is set up by clamping it onto one end of the table as shown in 

    the figure above.
2. One mass is placed into the inertia balance. The inertia balance is displaced to one side so  

    that it oscillates in a horizontal plane.
3. The time for 10 complete oscillations is measured using a stopwatch. This step is 
    repeated. The average of 10 oscillations is calculated. Then, the period of oscillation is 
    determined.
4. Steps 2 and 3 are repeated using two and three masses on the inertia balance.
5. A graph of T² versus number of masses, n is drawn.

Results: 

Graph of T² versus m: 

Discussion:
The graph of T² versus m shows a straight line passing through the origin. This means
that the period of oscillation increases with the mass of the load; that is, an object with a
large mass has a large inertia.

Conclusion:
Objects with a large mass have a large inertia. This is the reason why it is difficult to set
an object of large mass in motion or to stop it. The hypothesis is valid. 

Option 2: Using a saw blade

If the question asks for using jigsaw blade. 

Inference : Inertia depends on mass  

Hypothesis: The larger the mass, the larger the inertia 

Aim of the experiment:To study the effect of mass on the inertia of an object

Variables:
Manipulated: Mass, m
Responding: Period of oscillation, T
Constant: Stiffness of blade, distance of the centre of the plasticine from the clamp

Apparatus/Materials: Jigsaw blade, G-clamp, stopwatch, and plasticine spheres of
mass 20 g, 40 g, 60 g, 80 g, and 100 g

Setup:

Procedure:
1. One end of the jigsaw blade is clamped to the leg of a table with a G-clamp as per 
    the diagram drawn.
2. A 20 g plasticine ball is fixed at the free end of the blade.
3. The free end of the blade is displaced horizontally and released so that it oscillates. 
    The time for 10 complete oscillations is measured using a stopwatch. This step is repeated.  
    The average of 10 oscillations   is calculated. Then, the period of oscillation is determined.
4. Steps 2 and 3 are repeated using plasticine balls with masses 40 g, 60 g, 80 g, and 100 g.
5. A graph of   T² versus mass of load, m is drawn.

Result: 

 

Graph of   T² versus m:

 

Discussion:
The graph of T² versus m shows a straight line passing through the origin. This means that the period of oscillation increases with the mass of the load; that is, an object with a large mass has a large inertia.

Conclusion:
Objects with a large mass have a large inertia. This is the reason why it is difficult to set an object of large mass in motion or to stop it. The hypothesis is valid.

Courtesy Of http://shazillaphysics.blogspot.my/2012/03/inertia.html