PASCO ME-9430, Инструкция по эксплуатации, Страница: 5 / 24

Experiments
Plunger Cart
012-14781A 5
Experment 1: Kinematics (Average vs. Instantaneous Velocities)
Purpose
In this lab, the Plunger Cart will be used to investigate one dimensional accelerated motion. The
Plunger Cart will be launched over the floor using the built-in spring plunger. The Plunger Cart will
“decelerate” over the floor under the combined action of rolling friction and floor slope. You will be
able to establish whether or not the acceleration of the Plunger Cart is constant. This will be done
by initially assuming a constant acceleration and then by examining the results to see if they are
consistent with this assumption.
Theory
The cart will be allowed to roll to a stop. The distance D covered and the total elapsed time T from
launch to stop will be measured and recorded. The average velocity over this interval is given by
the following equation:
If the acceleration of the cart is constant as it rolls to a stop over the floor, then the initial instantaneous
velocity of the Plunger Cart at the final moment of launch is given by the following equation:
And the value of the acceleration would be given by the following equation:
If the acceleration and v
o
are known, then the time t
1
required to cover the distance d to some
intermediate point (i.e. short of the final stopping point!) can be calculated by applying the quadratic
formula to the following equation:
Calculated values of t
1
will be compared with directly measured values. The extent to which the
calculated values agree with the directly measured values is an indication of the constancy of the
acceleration of the cart.
Note your theoretical values in Table 1.1.
Equipment Needed
Plunger Cart
Metric Tape Measure
Stopwatch
Figure 1.1
av
D
v
T

Eqn. 1
0 av
2D
v 2v
T
 
Eqn. 2
Eqn. 3
0
2
0 v
v 2D
a
t T
T


   
Eqn. 4
2
0 1 1
1
d v t at
2
 