Why do the north poles of these two magnets repel each other?

Bone-strengthening physical activity done increases bone-mineral content and bone density in youth.

How do we measure or think of speed in the united states?

6–43 a food department is kept at 2128c by a refrigerator in an environment at 308c. the total heat gain to the food department is estimated to be 3300 kj/h and the heat rejection in the condenser is 4800 kj/h. determine the power input to the compressor, in kw and the cop of the refrigerator.