What is the definition of physical activity?

Which is the hottest layer of the Sun's atmosphere? A. photosphere B. chromosphere C. corona D. radiative E. convective

Tools used as nut crackers by chimps and birds

Which of the following describes a conductor? A. a rubber shoe sole with electrons stuck to the bottom. B. Electrons moving freely through a copper wire. C. a balloon with a small region of negatively charged electrons. D.

What causes the pressure that allows diamonds to form in the mantle A. Gravity from the sun B. Upward force from rocks in the core C. Downward force from rocks in the crust D. The moon's tidal forces

Which object would be considered to be in free fall? one that experiences both friction and centripetal force one that is truly weightless one that is slowed down by air resistance one with only gravity acting upon it

Fariza wears a red hat in her school play. On stage, she is lit by a spotlight shining only green light. When our eyes receive no light from an object, it looks black. Explain why Fariza's hat looks black on stage.

In a chemical reaction, one element replaces another element in a compound to form a new substance. Which of the following best describes this type of chemical reaction? Combustion Neutralization Double Replacement Single Replacement

If the Earth's crust contained twice as much iron as it does, would atmospheric oxygen buildup have been slowed down or sped up during the past 2.

Which of the following statements is true? A. Energy can change from one form to another. B. Matter and energy do not interact. C. Energy cannot be stored. D. Energy does not transfer from place to place.

Work is done when a force A. is exerted while pulling a wagon up a hill B. acts vertically on a cart that can only move horizontally C. is exerted by one team in a tug of war when there is no movement D.