Motion without Force

The dry ice puck rests on a smooth glass surface. With such apparatus we can study almost frictionless motion.
Dry ice inside the puck changes into a gas which escapes through the hole in the bottom of the puck.

The motion of a dry ice puck.

It moved from left to right while the light was flashed 24 times in 10 seconds, or every 10/24 s.
The scale at the bottom is in centimeters.
Here is a close approach to the ideal situation of motion without force.
The puck has nearly constant displacement in equal time intervals.

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Changes in Velocity when a Constant Force Acts

Unextended spring loop before being mounted on puck.	The loop extended. Whenever this loop is stretched the same amount., we seem to get the same force.

The flash photograph below shows the puck being pulled to the right.
The light flashes were separated by 10/24 s.
A constant force was applied by keeping the loop extension constant.

Dependence of Change of Velocity on Magnitude of Force

To apply twice the original force, we attach two identical loops to the puck.



The puck used in the first experiment is accelerated by twice the force used before.
The interaval between flashes is 10/24 s.