Science Questions

Clear explanations of the physics, biology, and chemistry concepts people look up most — grounded in how the world actually works.

• What is the difference between mass and weight?
  Mass is the amount of matter in an object and stays constant everywhere, while weight is the force of gravity acting on …
• What is Newton's first law of motion?
  Newton's first law states that an object stays at rest or keeps moving at a constant velocity unless acted on by an unba…
• What is the difference between mitosis and meiosis?
  Mitosis produces two identical cells for growth and repair, while meiosis produces four genetically different reproducti…
• What is the difference between an atom and a molecule?
  An atom is the smallest unit of a chemical element, while a molecule is two or more atoms bonded together — which can be…
• What is the greenhouse effect?
  The greenhouse effect is the process by which certain gases in the atmosphere trap heat from the sun, keeping Earth warm…