What's the most reliable source of energy on earth?

A flying bird action and reaction force

What is a major contributor of greenhouse gases in the atmosphere?

Which of the following is the most usable form of nitrogen to plants? ammonia nitrates nitrous oxide nitrogen gas

Who was the Governor of Anchorage, Alaska?

A particle is moving along the x-axis with velocity v (t) = sin2t. At time t = pi/2 it has position x = 3. Find the total distance, s traveled by this particle on the interval 0 < = t < = pi.

Which of Newton's laws, when combined algebraically with his law of universal gravitation, can be used to calculate Earth's mass? A) first B) second C) third

Why does a balloon filled with helium rise while a balloon filled with an equal volume of average atmospheric air does not? A. Helium has no mass, but air does. B. Helium increases the balloon's mass more than air. C.

Consider the following controls in an automobile in motion : gas pedal, brake, steering wheel. what are the controls in this list that cause an acceleration of the car?

What material are oil pipelines made from?

3/129 A 175-lb pole vaulter carrying a uniform 16-ft, 10-lb pole approaches the jump with a velocity v and manages to barely clear the bar set at a height of 18 ft. As he clears the bar, his velocity and that of the pole are essentially zero.