Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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Measurement
Motion In One Dimension
Motion In Two Dimensions
Newton's First Law
Newton's Second Law
Weighing
video  - The Atwood Machine
video  - Helium Balloon Accelerometer
Float Accelerometer
Newton's Third Law
Statics Of Rigid Bodies
Applications Of Newton's Laws
Gravity
Work and Energy
Momentum
Rotational Motion
Properties of Matter

video  - The Atwood Machine

Purpose:

To illustrate Newton's Second Law.

Procedure:

DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 114MB size

• For m1 = m2 = 550g, the masses do not accelerate (ie. stay motionless or move at constant speed)
• For m1 = 550g and m2 = 600g, the measured time it takes m2 to accelerate from rest and fall 1.5m is 2.79s.
• For m1 = 550g and m2 = 650g, the measured time it takes m2 to accelerate from rest and fall 1.5m is 1.97s.

You must take into account the mass of the pulley Mp = 173g due to moment of inertia of the disk.

One can compute the acceleration from the height mass m2 falls: h = 1/2 at2 and compare with g.

Hints:

If one assumes the pulley is massless, the calculated time it takes m2 to fall 1.5m is:
• 2.60s and 1.84s for m2 = 600g and 650g respectively
If one takes into account the pulley mass Mp = 173g, the calculated time it takes m2 to fall 1.5m is:
• 2.80s and 1.97s for m2 = 600g and 650g respectively

Equipment:

• Timer
• 1 2-meter stick
• Atwood machine with attached pulley
• Weights