Science Models
Science Fair Projects

Published on Feb 13, 2016


The objective:

Hypothesis: Friction constitute most of the resisting energy of the motor Objective is to Measure how much energy is lost to Friction in a Motor Assumption: Rotating motor has a resisting force acting against it in the opposite direction (Rotational Friction)



Bring out the stripped hard drive, tachometer, D.M.M, paper clip and the power supply. Straighten out the paper clip, and then cut off two inches off the paper clip.

After that is done, shape the paper clip in U-shape. - The power supply will have many cables, use the biggest cable, and then plug in the paper clip at the top where the green wires is and the black wire diagonal from it. Then connect the wire that reads p-3 into the hard drive.

Bring out the black construction paper and trace the hard drive disk onto the black paper. Draw two propellers onto the black construction paper. Cut out the propellers that you have just made.

Later, there will be the rest of the paper disk that's left over. Cut the part out. - Assemble the disks back together. While the disk is spinning, point the tachometer at the disk.

Find out the weight of the motor and discs, which is equal to mass. Record you results. Next, find the velocity or RPM (Rotation Per Minute), record your results.

Then plug the Mass and Velocity in to the equation K(Kinetic Energy)= 1/2m(Mass)v(Velocity)^2


400 watt Power Supply, Stripped Hard Drive, Tachometer, Reflective tape, Black construction paper, Tape, Screw driver set, Compass, Ruler, D.M.M.( Digital Multi Meter ), Stopwatch, Calculator, Scale, 1 Paper Clip


Rotational Kinetic energy of the running motor is the energy lost to friction. Angular velocity = Omega (Ѳ)/t Where Omega (Ѳ) = angle traveled, t = in time t, Rotational inertia = Ѳ/t. Per the experiments the Results are: Work/second = 9.81 joules per 4 seconds, That equals 2.425 joules per second or 2.425 watts.


Our hypothesis is correct i.e. Friction constitute most of the resisting energy of the motor - Every second the motor runs, it uses 2.424 joules of energy in the backward direction

This project was to find out how much energy is lost to friction when it opposes motion in angular direction.

Science Fair Project done By Satyaprit Das