Which types of galaxies tend to be made up of very old stars and contain very little gas and dust matter?

The total power consumption by all humans on earth is approximately 1013 W. Let's compare this to the power of incoming solar radiation. The intensity of radiation from the sun at the top of the atmosphere is 1380 W/m2. The earth's radius is 6.

Explain how reflection and refraction are similar to each other and different from each other.

If a train is 100 kilometers away, how much sooner would you hear the train coming by listening to the rails (iron) as opposed to listening for it standing by the track?

Would it be A? What portion of the electromagnetic spectrum can human eyes detect? A. visible light B. visible light and infrared light C. infrared light D. infrared light and ultraviolet light

Substance can undergo physical change or chemical change? What is difference between these two kinds of changes?

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

Is a lung a living organism, why or why not?