PASCO ME-8930 SMART TIMER - Manual (Page 21)

012–06734A Smart Timer
17
Experiment Two: Newton’s Second Law
EQUIPMENT AND MATERIALS REQUIRED
• Smart Timer (ME-8930) • Photogate (ME-9498A)
• Dynamics Cart (ME-9430 or ME-9454) • Photogate Bracket (part no. 003-04662)
• Dynamics Cart Track (ME-9429A) • Mass Hanger and Mass Set (ME-9348)
• 500 gram bar mass • Ohaus Triple-Beam Balance (SE-8707) or similar
• Super Pulley (ME-9450) • Physics String (SE-8050)
Purpose
The purpose is to verify Newton’s Second Law, F = ma.
Theory
Newton’s Second Law, F = ma, is a description of the relationship between F, the net force
acting on the object of mass m, and a, the resulting acceleration of the object. For a cart of
mass m
1
on a horizontal track with a string attached over a pulley to a mass m
2
(see Figure
2.1), the net force F on the entire system (cart and hanging mass) is the weight of hanging
mass, F = m
2
g, assuming that friction is negligible.
According to Newton’s Second Law, this net force should be equal to ma, where m is the
total mass that is being accelerated, which in this case is m
1
+ m
2
. This experiment will
check to see if m
2
g is equal to (m
1
+ m
2
)a.
Procedure
1. Level the track by setting the cart on the track to see which way it rolls. Adjust the
leveling screw at the end of the track to raise or lower that end until the cart placed at
rest on the track will not move toward either end.
2. Use the balance to find the mass of the Dynamics Cart and record the mass in Table 2.1.
3. Attach the Super Pulley to the end of the track as shown in Figure 2.1.
4. Connect the Photogate to the Smart Timer, and adjust the Photogate so that when the
pulley turns, the spokes of the pulley will block the photogate beam.
Dynamics Cart to Smart Timer
Adjustable
End Stop
Photogate
Photogate
Bracket
Figure 2.1
Experiment setup to determine the acceleration of the masses
Mass Hanger and Mass
Super
Pulley
IDS Track
m
1
m
2