Why do you think people had a hard time accepting the idea of gravity as a force that keeps planets in their orbits?

What are the necessary conditions for fusion?

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?

Dc versus ac problem. suppose your dc power supply is set to 15 v and the vertical setting on the oscilloscope is at 5 v/div. how many divisions will the trace deflect if you connect the output of the power supply to the scope with the a input switch set on dc? how many divisions if the switch is on ac?