A curious physics student asked her teacher “ how quickly is earth moving through space?” using the concept of relative velocity, explain why this question does not have an answer. 

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Question 11 of 13 (1 point) jump to question: a stairway, ladder, or ramp must be present in excavations in which of the following situations? a. all trenches must have access/egress b. the trench is more than 15 feet wide but only 1 ½ feet deep c. the trench is more than 4 feet deep and the devices must be within 25 feet of all workers

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)?