Material: 

2. 2 to 3 Kg weight with hooks on both ends

3. roll of toilet paper

Future Quicktime Movie and photos of the demo to go here!

Procedure:

1. suspend weight from top string with left hand

2. pull on lower string with a quick pull with the right hand.

3. replace string(s) and repeat pulling with a slow steady pressure.

Experiment #2

1. hold or hang a roll of toilet paper in normal dispensing position.

2. pull on paper with a quick pull.

3. pull on paper with a slow steady pressure.

Questions:

2. Why does a slow pull on the string break it above the weight?

3. Why does a sharp jerk break the string below the weight?

4. Which of the two breaks makes special use of the weight's inertia?

RATIONALE:

string below and above the weight. Due to the mass of the weight, 

the strain above the weight is much larger than below. The 

string snaps wherever the strain is highest.

When a sharp jerk is exerted on the string, the inertia of 

the weight keeps the strain below the weight. Although there is 

some strain above the weight, compared to the strain below the 

weight the strain in the latter is still higher, and the string

snaps below the weight.

APPLICATION: