4. A roller coaster car travels along the track shown in the diagram below. At which position on the track are the kinetic and potential energy of the roller coaster car almost equal to each other?
O A. Position 1
OB. Position 2
OC. Position 3
OD. Position 4

In physics the desire of an object to keep doing what it is doing is termed?

Along the line connecting the two charges, at what distance from the charge q1 is the total electric field from the two charges zero? express your answer in terms of some or all of the variables s, q1, q2 and k =14ï€ïµ0. if your answer is difficult to enter, consider simplifying it, as it can be made relatively simple with some work.

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.