The force of friction between an object and the surface upon which it is sliding is 15N. The mass of the object is 20kg. What is the coefficient of kinetic friction?
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Which of the following is an example of units for speed

In a hydrogen molecule there are a total of four charges, 2 protons in the two nuclei, and 2 electrons. how many unique charge-pairs are there (without double counting)?

During the past 150 years in the united states, how did energy consumption compare to population growth