Thames & Kosmos Physics Workshop handleiding

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Thames & Kosmos

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Handleiding

In reality, what we have determined with our locator is the center of gravity on the

object’s surface — also known as center of area. In order to determine how deep the

actual center of gravity lies within the three-dimensional object, we would need a

more precise apparatus. In the case of the plate or the rods, this three-dimensional

center would be about halfway through the object at the spot beneath its center of

area.

WORKSHOP 2: CENTER OF GRAVITY LOCATOR

Step 1: We will use one of the base plates as the object of which we would like to

determine the center of gravity. Tape a sheet of white paper to the front of the base plate.

Suspend the base plate from the lower axle by one of its corner holes. It should hang

freely without hiing anything. Wait until the plate stops moving and then push carefully

on the axle until the plate almost touches the string. Gently press the string against

the plate and use a felt-tip pen to mark two spots, one at the top and one lower down,

where the string touches the paper taped onto the plate. Now remove the plate from its

hanger, pull back the axle, and re-hang the plate from an adjacent corner hole (a diﬀerent

corner hole that is not the one diagonally across from the original corner hole). Repeat

the procedure with the felt-tip pen. Remove the plate again and draw two lines, each

connecting the pair of marks you made each time you suspended the plate. The point

where the two lines cross is the plate’s center of gravity.

Tip: If the string gets pulled towards the plate, let it stick a lile so both components can

release their charge and the experimental results aren’t skewed. The araction is caused

by a static electrical charge between insulating materials.

Step 2: Now let’s change the object by aaching two long rods along the long edge of the

plate. What do you notice? The center of gravity has moved towards the side where the

two rods have been aached, or more speciﬁcally in the direction of the center of gravity

of the rods themselves. Test the result by trying to balance the plate on your ﬁngertip just

at the spot where you have calculated its center of gravity to be.

EXPERIMENT 2: FINDING YOUR CENTER

KEYWORD: CENTER OF

AREA

The center of area is the center of gravity

projected onto the surface of an object.

The upper axle with the string may be

moved forward or backward as needed.

The center of gravity of the suspended

base plate can be changed by aaching

two long rods. See Experiment 2.

8 9

Done!

Thread the

string through

the x-shaped

opening in the

small sprocket

wheel.

Aach

rods to

change

the center

of gravity.

String



Bekijk gratis de handleiding van Thames & Kosmos Physics Workshop, stel vragen en lees de antwoorden op veelvoorkomende problemen, of gebruik onze assistent om sneller informatie in de handleiding te vinden of uitleg te krijgen over specifieke functies.