In a perfectly inelastic collision the object stick together after the collision to form a
single object whose mass is the sum of the original objects. The momentum equation
is, for this case:
p1,i +p2,i =p f , with p2,i =0
In terms of the velocity:
will take some practice to maintain the level of the mass off the floor. The two
major variables are "cranking speed" and the small "tension" on the free end of
the cord. One may use the clamp to keep the cord centered on the cylinder if
Such a motion is called simple harmonic motion (SHM): harmonic, because it is
sinusoidal and simple, since it is represented by a single sinusoid rather than a linear
combination of several of them. As you know from trigonometry, a sinusoid is a
You will study two different kinds of SHM, that of a weight attached to a spring
and that of a pendulum.
A weight attached to a spring is schematically
Fig. 1. Harmonic Motion of a mass on a frictionless surface.!
The weight is placed on top of a friction
This means that the addition of 1 calorie of heat transfer or the
performance of 4.186 Joules of work on the system accomplishes the same
change in the internal energy of the system. 1 The ratio, 4.186 J/cal, is known, for
Measure the period of the spring for vertical oscillations using several different masses
! by averaging the time required for 10 oscillations. Do not use the photogate timers.
Plot T2 versus m for the spring and see how well this approximates a str
if you think carefully about it, the experiment will give you a good physical sense or
intuitive feel for the concepts of gravitational and inertial mass.
The two different concepts of mass can be summarized in the following way:
(1) Gravitational mass, m
You will study and observe the equivalence of gravitational mass and inertial mass.
Learn how to setup an air track with two cars to observe momentum conservation.
Learn how to measure the speed of cars on an air track.
Measure the ratio of gravitation
velocity Figure 1 Schematic of the car setup.
you would find for the two trials that the ratios
vA,1 = vA,2 = constant.
of vA and vB .
is expected to be a constant, independent of the individual
If you repeat th
Measure the period of a pendulum (using the same mass) for six different lengths,
from a very long one down to about 20 cm. Keep the angle of the oscillations less
than 10 from the vertical.
Do this twice in each case and take an average to