If a force of 20kN acts on a circular rod of diameter 10mm, calculate the stress in the
rod.
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Which surface feature of the moon is characterized by mountainous areas? terrae craters maria regolith

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

The mass of a bowling ball is 10 kg and the mass of a ping pong ball is 0.015 kg. if the two objects are 5 meters apart, what is the gravitational force ?