A sample of a material has 200 radioactive particles in it today. Your great-grandmother measured 400 radioactive particles in it 100 years ago. 100 years from today, how many radioactive particles will the sample have?

It is well known that lightning is seen before the thunder is heard. Wavelengths of electromagnetic and sound waves can be the same. Imagine that the wavelengths from the lightning and thunder are the same, what can be said about their frequencies?

How much do a steel BB weight?

Once their strength is exceeded, rocks near the surface behave like A. modeling clay. B. most metals. C. glass objects. D. caramel candy.

Explain how a charged amber rod can lift tiny bits of paper despite being under the gravitational force of the entire mass of the earth.

The de Broglie relation λ=h/p can be rewritten in terms of the wave number k as p=kℏ. Recall that wave number is defined by k=2π/λ. Using the fact that λ=v/f, find the wave numbers k1 and k2 corresponding to frequencies f1 and f2.

If element X has 17 protons, how many electrons does it have?

A 2.0-kilogram laboratory cart is sliding across a horizontal frictionless surface at a constant velocity of 4.0 meters per second east. What will be the cart's velocity after a 6.0-newton westward force acts on it for 2.

A boat floats with 25% of its volume under water. a. What is the boatâs density? b. If the boat was made from 500 kg of metal, what is the volume of the boat? (Assume the air in the boat has negligible mass and density) c.

Why does each mineral have their own property, different from every other mineral?

Earth's tallest mountain ranges are found at plate boundaries