PASCO ME-6815 PROJECTILE CATCHER ACCESSORY User Manual

Page 24

Projectile Catcher Accessory

012-05091E

In Gate-Pulse mode, the computer will show five
numbers. They are:

time 1 Duration of first Photogate’s blockage by

the ball

time 2 Time between unblocking first Photogate

and blocking second

time 3 Duration of second Photogate’s blockage

by the ball

time 4 Time between unblocking second

Photogate and blocking third with cart

time 5 Duration of third Photogate’s blockage by

the cart.

Add the first two times to find the total time it took
the ball to travel the 10 cm between Photogates,
and use this time to calculate the ball velocity. Ig-
nore the third and fourth times given. Use the fifth
time to calculate the cart velocity.

Analysis

2. If you are using the gate-pulse mode rather than

motion timer, be sure to use the actual length of
whatever blocked the third Photogate the first time
to calculate cart velocity. In other words, if the
photogate is aligned with the catcher slots, the
length would be 4 cm; but if the photogate is not
aligned with these slots, then use the entire length
of the catcher.

4,8. The initial and final momentum should be within

10% of each other. They will not be exact be-
cause of inaccuracy in measuring velocity and
because of frictional losses to the cart track.

5,6. The theoretical loss of kinetic energy is

Actual loss will be slightly greater than this, due to
friction between the cart and track.

Answers to Questions

1. Momentum is conserved, within the limits of mea-

surement for this experiment.

2. Kinetic energy is not conserved.

% lost = 1 –

+ m

x 100%