A hydrogen bond is the electromagnetic attraction between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen. This is not a sharing of electrons, as in a covalent bond. Instead, this is an attraction between the positive and negative poles of charged atoms.
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The correct answer is C: the gravitational forces due to the sun and the moon cancel each other's effect.
They feed on dead, decaying, organic matter.
Physics is very common in our lives, and of course this also applies to the performance of a runner.
For example, he or she needs to understand the air resistance when running, they may need to find a way to reduce the most air resistance that is against them so that they can show their best performance.
Or another example is they may need to find out the friction acting on between their feet and the track, they may need to adjust their training in different textures of running tracks, as each acts a different amount of friction.