Why are some rocks smooth and others rough?

What play did Mr. and Mrs. Lincoln plan to see at Ford's Theater on the night Mr. Lincoln was assassinated?

A hypothesis is? close agreement by competent observers of observations of the same phenomena. a guess that has been tested over and over again and always found to be true. an educated guess that has yet to be proven by experiment.

An air bubble at the bottom of a lake 43.5m deep has a volume of 1.00cm/cubed. If the temperature at the bottom is 5.5 degrees celcius and at the top 21.0 degrees celcius, what is the volume of the bubble just before it reaches the surface. ... ?

Definition of artficial and natural radioactivity

Can an electric field exist in a vacuum?

Mass m1 is has an initial velocity v1i. Mass m1 collides with a stationary mass m2. The net external force on the two particle system is zero. If the two masses stick together after the collision, then the final speed vf of the two masses is:

What can one say for sure about element #99, Einsteinium (Es)) ? a) There's no such element! b) It is an alkali metal. c) It is radioactive. d) It has 253 neutrons. e) It increases one's 1. Q. slightly when swallowed.

What is the pH of neutral substance?

The velocity of a wave depends only upon the ... ?

When studying atoms, scientists can ignore the blank force between charged particles that make up the atoms because it is many millions of times smaller than other forces in the atom