A man is standing between two hills. He fires a gun. He hears two echoes: one after 0.3s and another after 0.5s. What is the distance between the two hills?

Hydrogen and helium are both members of?

Which of the following are appropriate acceleration units?

Agraduated cylinder contains 63.0 ml of water. a piece of gold, which has a density of 19.3 g/ cm3, is added to the water and the volume goes up to 64.5 ml. calculate the mass in grams of the gold that was added to the water. explain how you got your answer.