Experiments
Plunger Cart
012-14781A
9
Experiment 3: Newton’s Second Law (Predicting Accelerations)
Purpose
In this lab, a small mass m will be connected to the cart by a string as shown in Figure 3.1. The
string will pass over a pulley at the table’s edge so that as the mass falls the cart will be accelerated
over the table’s surface. As long as the string is not too elastic and there is no slack in it, both the
falling mass and the Plunger Cart will have the same acceleration. The resulting acceleration of this
system will be experimentally determined and this value will be compared to the acceleration
predicted by Newton’s Second Law.
Theory
The cart will be released from rest and allowed to accelerate over a distance d. Using a stopwatch,
you will determine how long it takes, on average, for the cart to move through the distance d. An
experimental value for the cart’s acceleration a can be determined from:
Assuming that the tabletop is truly horizontal (i.e. level), Newton’s Second Law (F = ma) predicts
that the acceleration of this system will be:
Equipment Needed
Plunger Cart
Pulley and Pulley Clamp
Mass Set
Balance
Stopwatch
String
Paper clips
Block (to act as bumper)
Bumper Block
Paper clips
Figure 3.1
2
2d
a
t
2
1
d
at
2
which leads to
(Experimental Value)