PASCO ME-9215B Photogate Timer - Manual (Page 15)

012-06379B Photogate Timer
11 ®
Experiment 4: Newton’s Second Law
EQUIPMENT NEEDED:
-Photogate timer with Accessory Photogate (or two Photogate Timers)
-Air TrackSystem with one glider
-Masses
-Pulley -Pulley Mounting Clamp
-Universal Table Clamp
Introduction
There’s nothing obvious about the relationships governing the motions of objects. In
fact, it took around 4,000 years of civilization and the genius of Isaac Newton to figure
out the basic laws. Fortunately for the rest of us, hindsight is a powerful research tool.
In this experiment you will experimentally determine Newton’s second law by examin-
ing the motion of an air track glider under the influence of a constant force. The con-
stant force will be supplied by the weight of a hanging mass that will be used to pull the
glider. By varying the mass of the hanging weight and of the glider, and measuring the
acceleration of the glider, you’ll be able to determine Newton’s second law.
Procedure
c
Set up the air track as shown in Figure
4.1. Level the air track very carefully by
adjusting the air track leveling feet. A
glider should sit on the track without
accelerating in either direction. There
may be some small movement of the
glider due to unequal air flow beneath the
glider, but it should not accelerate
steadily in either direction.
d
Measure the effective length of the glider, and record your value as L in Table 4.1.
e
Mount the hook into the bottom hole of the cart. To counterbalance its weight, add a
piece of similar weight on the opposite end as shown on Fig. 4.1.
f
Add 50-60 grams of mass to the glider using 10 or 20 gram masses. Be sure the masses
are distributed symmetrically so the glider is balanced. Determine the total mass of your
glider with the added masses and record the total as m in Table 4.1.
g
Place a mass of approximately 5-10 grams on the weight hanger. Record the total mass
(hanger plus added mass) as m
a
.
h
Set your Photogate Timer to GATE mode.
i
Choose a starting point x
0
for the glider, near the end of the track. Mark this point with a
pencil so that you can always start the glider from this same point.
j
Press the RESET button.
k
Hold the glider steady at x
0
, then release it. Note t
1
, the time it took for the glider to pass
through the first photogate, and t
2
, the time it took for the glider to pass through the
second photogate. Repeat this measurement four times. Take the average of your mea-
sured t
1
's and t
2
's and record these averages as t
1
and t
2
in Table 4.1. panel
l
Set the Photogate Timer to PULSE mode.
11
Press the RESET button.
Accessory
Photogate
Hook
Photogate
Timer
m
a
String
Pulley
Mounting
Rod
Counter
Balance
Glider
x
0
Figure 4.1: Equipment Setup
Tableclamp