What causes some materials to have a magnetic fields?

The force of gravity causes all objects near earth's surface to fall with an acceleration of 20 m/s2. true or false.

A proton has mass 1.7 ✕ 10-27 kg. what is the magnitude of the impulse required to increase its speed from 0.991c to 0.994c?

What's the difference between instantaneous and average velocity? How do you calculate both of them?

There is a form of light that is very energetic and can cause damage to living cells and tissues. The Sun emits this type of light, but much of it is blocked by ozone in the atmosphere.

Dalton theorized that atoms are indivisible, but the discovery of particles changed this theory. scientists now know that atoms are made up of electrons, which have a charge; which have a positive charge; and, which are neutral.

Two identical objects are moving directly toward one another at the same speed v. ~v - ~v m m What is the total kinetic energy of the system of the two objects?

Why would a long series of gradual ramps be better than one short, steep ramp for moving heavy blocks of stone?

Why are some liquids more viscous than others?

If a person weighs 125 lbs, 8oz., how many mg does s/he weigh

An iron rod is: A:a good conductor of heat and electricity, but not magnetic B: magnetic and a good conductor of heat, but is an insulator of electricity C: magnetic and a good conductor of heat and electricity D: not magnetic and an insulator of