When the ruler is hit sharply, one washer drops to the floor while the other is launched to the side.


If you shoot a bullet horizontally out over a lake, and drop a bullet at the same instant, both bullets will hit the water at the same time. The same experiment can be done in a classroom with rulers and washers.


To Do and Notice

Push the pin into the center of the ruler.

Place the ruler near the corner of the table, parallel to one edge of the table, about 2.5 cm (1") from the edge, so that about half the ruler sticks over the edge of the table.

Put one washer on top of the ruler about 5 cm (2") outside the edge of the able. When the ruler moves out from under this coin it will drop straight to the ground.

Put the other coin between the ruler and the edge of the table near the end of the ruler.

Hold the push pin in one hand.

Hit the end of the ruler hat is outside the table so that the ruler rapidly rotates about the pushpin, dropping one coin to the floor while shooting one coin to the side rapidly.

Notice that both coins hit the floor at the same time.

What's Going On?

Objects accelerate toward the surface of the earth at the same rate regardless of their motion.

The moving coin and the initially stationary coin fall to the ground in the same time.


Return to Draft Activities

Scientific Explorations with Paul Doherty

© 2003

21 August 2003