Q. Current of 83 mA flows through the resistor shown in the diagram. The emf of the battery is 4.50 V. (a) What is the resistance of the resistor? (b) In what direction does the current flow through the resistor?
Q. Acentimeter ruler, balanced at its center point, has two coins placed on it, as shown in the figure. One coin, of mass M1=10 g, is placed at the zero mark; the other, of unknown mass M2, is placed at the 4.7 cm mark. The center of the ruler is at the 3.0 cm mark. The ruler is in equilibrium; it is perfectly balanced.
Does the pivot point (i.e., the triangle in the diagram upon which the ruler balances) exert a force on the ruler? Does it exert a nonzero torque about the pivot?