Video Notes - Newton's First Law

If you weigh 150 pounds and distribute your weight equally between two bathroom scales, how much will each scale read?

75 pounds

What did Galleo state about an object in motion?

An object in motion stays in motion until a force stops it.

Although Aristotle recognized that objects move because a force is applied to them, what was he unable to explain?

Aristotle couldn't explain why objects keep moving when a force is no longer applied to them. For example, why does an arrow keep flying through the air after it's been shot out of the bow?

How does Paul Hewitt define mass?

Inertia.

Paul Hewitt suspends two clay balls over his head by a coat hanger. If one clay ball is hanging before his face, he can see the one behind him by turning around. The clay balls stay put because of what tendency?

Inertia. Objects at rest stay at rest unless a force acts upon them.

To say that an object moves in a straight-line path at constant speed, what about its velocity?

It says that constant velocity is operating in the absence of a force (intertia)

What is another name for Newton's first law?

Law of Inertia

What does Newton's first law explain?

Newton's first law explains why an object keeps moving when no force is present.

Harry, a painter, is suspended in a bosun's chair by two ropes. what is the tension in each rope?

One half of Harry's weight.

Paul lies on a table with the anvil on his stomach and has a student hit the anvil with a sledgehammer. Why doesn't paul get hurt?

Paul didn't get hurt because he was protected by the mass of the anvil. Because the anvil weighed a lot, it had little tendency to change (inertia). He would have been hurt if he used a small piece of wood.

What is the difference between mass and weight?

Weight-the force of gravity on an object (heaviness) Mass-measure of an object's resistance to change. (inertia).

Is another word for change

acceleration

is resistence to change

inertia

Objects in equilibrium have a net force of

zero

What is the acceleration of a moving object if no net force is applied to it?

zero