Convection currents form when warm air rises and cold air sinks. what causes the warm air to rise and the cold air to sink? a. a difference in climate b. a difference in density c. a difference in weather d. a difference in substance

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=