Why it's dangerous to jump from a moving bus?

Lets say that an object of a certain volume has a certin mass. what happens to its mass when you double its volume?

Let f(x) = x4- 8x2 . find the relativeextrema of this function using the second derivative test.

When applying kirchhoff's rules, one of the essential steps is to mark each resistor with plus and minus signs to label how the electric potential changes from one end of the resistor to the other. the circuit in the drawing contains four resistors, each marked with the associated plus and minus signs. however, one resistor is marked incorrectly. which one is it?