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PEKA 4
PEKA 4
Relationship between force and acceleration when mass is constant.
Problem
Statement
An object accelerates when acted upon by a force. What happens to the
acceleration of the object if the force acting on it increases and the mass of the
object remains constant?
Inference
Force influences the acceleration of an object.
Hypothesis
The acceleration of an object of constant mass will increase when the force acting
on it increases.
Aim
To study the relationship between force and acceleration of an object when its
mass is constant.
(a) Manipulated : Force
Variables
(b) Responding : Acceleration
(c) Fixed : Mass
Apparatus
Materials
Operational
Definition of
Variables
Procedure
Ticker timer, 12 V a.c. power supply, 2 identical trolleys and an inclined plane
with a pulley at one end, Triple Beam Balance
Thread, Slotted weights, 50g, 100g, 150g (Or 50g, 80g, 100g)
Acceleration : Rate of change of velocity that can be determined by analyzing the
ticker tapes.
Force : Force is achieved by using slotted weights attached to the trolley by a
non-elastic thread.
Diagram of Apparatus
Ticker
Timer
Ticker
Tape
Trolley
Thread
Friction compensated
inclined plane
Pulley
Lab Bench
Slotted
Weights
Unit Physics , SMJK Yu Hua
Pradeep Kumar
PEKA 4
1. Arrange the apparatus as shown in the diagram. The runway must be tilted to an
angle to compensate for friction.
2. Switch on the ticker timer.
3. Use a 50g slotted weight and attach it to the thread.
4. Release the slotted weight and let it fall freely to the ground.
5. Analyse the ticker tape to determine the acceleration, a of the trolley and record
the value in the form of a table.
6. Repeat procedures 4 and 5 using 100g and 150g slotted weight to increase the
force applied uniformly.
7. Plot the graph of acceleration against force.
Method
Table of
Results
1. Plot the graph of acceleration against time using the 10 ticks tiker tapes from
the experimental results. From each graph of 10 ticks, calculate the acceleration
2. Draw a table and record the data.
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50g force
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. 100
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150g force
Acceleration Calculations
50g force (0.5N)
100g force (1.0N)
150g force (1.5N)
Unit Physics , SMJK Yu Hua
Pradeep Kumar
PEKA 4
Force, F/N
0.5
1.0
1.5
Acceleration, a/cm s2
(Use actual values from your experimental investigation)
Graphs
1. Plot the graphs of acceleration against force in Figure 1.
Discussion
1. From the graph, state the relationship between acceleration and force when the
mass of the trolley is constant. Does the result support your hypothesis?
The graph of acceleration against force shows that the bigger the force the bigger
the acceleration of the trolley when its mass is constant. The hypothesis is
supported.
2. Write a mathematical relationship between the acceleration and force when the
mass is constant.
The acceleration, a is directly proportional to the force, F when the mass is
constant, a  F, m constant.
Conclusion
Acceleration of the trolley is directly proportional to the applied force when the
mass is kept constant.
Precaution
Compensation for friction by tilting the runway to a certain angle is done by
repeatedly increasing the angle of inclination of the runway in small steps until
the trolley moves with a constant velocity when it is released
Unit Physics , SMJK Yu Hua
Pradeep Kumar