physics chapter three

Copernicus

Developed the first modern theory of a sun-centered universe

The law of inertia states that an object

*will remain at rest until acted on upon an outside force *will continue moving at the same velocity unless an outside force acts on it. *will continue moving in a straight line unless an outside force acts on it.

inertia

reluctance any material object has to change in its state of motion.

The following forces act on an object: 20-N North, 50-N South, and 40-N West. What is the magnitude of the net force?

50 N

After a cannon ball is fired into frictionless space, the amount of force needed to keep it going equals

0

A 10-N force and a 30-N force act on an object in opposite directions. What is the net force on the object?

20 N

On the surface of Jupiter the acceleration due to gravity is about 3 times that on Earth (10m/sec/sec) How much would a 100 Kg rock weigh on Jupiter? Force = mass x gravity

3000

Galileo

Publicized Copernicus's findings; used the telescope to study moon and planets; added discoveries concerning the laws of gravity; condemned by the Catholic church for his work.

The astronomer Copernicus was the first person to publicly state that the Earth

revolves around the sun

Newton

This physicist developed the law of universal gravitation and further caused the decline of the old system of science

the law of inertia applies to..

both moving and nonmoving objects

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to

follow a straight line path

SI unit force

killogram

what is the difference between mass and weight?

mass is the amount of an object and weight is the force due to gravity. mass is a kilogram.

Which has more mass, a kilogram of feathers or a kilogram of iron?

neither the masses are equal

If a hockey puck slides on a perfectly frictionless surface it will...

not slow down

mass

the amount of matter in an object

net force

the combination of all forces that act on an object

Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?

to nearly the same height as it originally started