Energy
Aim: understanding of energy, work and conservation of energy
Objectives
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Kinetic and potential energy
Conservation of energy
A falling object from a height will convert its potential energy (mgh) to kinetic energy (½mv2) as it
acquires velocity. Design an experiment that measure the power and energy produced by a falling mass.
Before Practical Session
You need to read about the following instruments and note down the specifications
 Rotary sensor
 Energy sensor
Safety Issues
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Pay attention while connecting the motor to energy sensor to avoid short circuit.
Experiment 1: Potential energy and Kinetic energy of a falling mass
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First measure the mass of the different objects you are given and label them. The masses should
be within the range of 50 g to 150 gm.
Using a string that is about 75 cm long hang one of the object to the rotary motion sensor wheel
and wound the string around the wheel until the mass hangs about 15 cm from the wheel.
Configure the Lab Quest to start capturing reading when the rotary sensor rotates by 1 rad as
the mass is falling. It should capture data for a duration of 2 seconds at the rate of 50
samples/second
Let the mass fall as it pulls the string and rotate the wheel.
Capture the angular displacement, velocity and acceleration due to the mass falling because of
gravity
Analysis
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Using this data calculate the kinetic energy and potential energy of the object as it falls the
length of the string
Was there a conservation of energy between Potential energy and Kinetic Energy?
Experiment 2: Electric Energy generated by a falling mass
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Connect a DC motor to the rotary sensor using a rubber ring.
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Connect the connections of the DC motor to Energy sensor. Make sure that the wires are not
connecting to each other shorting the motor or the sensor.
Connect the energy sensor to LabQuest
Repeat steps in experiment 1 and capture angular displacement, velocity and acceleration in
addition to voltage, current , power and energy generated by the DC motor
Analysis:
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Was energy conserved?
What speed did the falling mass produce the maximum electric power? What was the kinetic
energy and potential energy at that point?
What is the total energy produced by the falling mass in the first 3 seconds?
What equation will describe the relationship between the mechanical (potential and electrical)
energy and the electrical energy?
Submission:
 LabQuest file with data and graphs
 Calculation linear displacement, velocity and acceleration as the mass is falling
 Answer to the given questions.