20
Photogate Timer
012-06379B
®
photogates. Record t
1
, the time during which the glider blocks the first photogate, and t
2
, the
time during which it blocks the second photogate. (If you have an ME-9215A Photogate
Timer, the memory function will make it easier to measure the two times. If not, someone
will need to watch the timer during the experiment and quickly record t1 before the glider
reaches the second photogate.)
l
Repeat the measurement several times and record your data in Table 8.1. You needn’t release
the glider from the same point on the air track for each trial, but it must be gliding freely and
smoothly (minimum wobble) as it passes through the photogates.
11
Change the mass of the glider by adding weights and repeat steps 7 through 10. Do this for at
least five different masses, recording the mass (m) for each set of measurements. (If you have
time, you may also want to try changing the height of the block used to tilt the track or the
distance between the photogates.)
d =
h =
D =
L =
m =
Table 8.1 Data and Calculations
m
θ
t
1
t
2
v
1
v
2
E
k1
E
k2
Δ
(mgh)
Data and Calculations
c
Calculate
θ
, the angle of incline for the air track, using the equation
θ
= arctan (h/d).
For each set of time measurements:
d
Divide L by t
1
and t
2
to determine v
1
and v
2
, the velocity of the glider as it passed through
each photogate.
e
Use the equation E
k
= (1/2)mv
2
to calculate the kinetic energy of the glider as it passed
through each photogate.
f
Calculate the change in kinetic energy,
Δ
E
k
= E
k2
- E
k1
.
g
Calculate
Δ
h, the distance through which the glider dropped in passing between the two
photogates (
Δ
h = D sin
θ
, where
θ
= arctan h/d).
h
Compare the dimetic energy gained wiht the loss in gravitational potential energy. Was me-
chanical energy conserved in the motion of the glider?
