1)A parallel-plate capacitor holds charge q and is not connected to anything. The distance between the plates is now increased. The electrical energy stored on the capacitor
decreases;
remains the same;
increases;
can do any of the above, depending on how the capacitance changes
2)When a mechanical or electromagnetic wave goes from medium to another, it undergoes a change in
amplitude only
both speed and wavelength
speed only
wavelength only
3)Two idential rooms in a perfectly insulated house are connected by an open doorway. The temperature in the two rooms are maintained at different values. The room which contains more air molecules is
the one with the higher temperature;
the one with the lower temperature;
the one with the higher pressure;
neither, since both have the same volume
4)Three airplanes, A,B and C, each release an object from the same altitude and with the same initial speed v0 with repsect to the ground. At the moment their object is released, A is flying horixontslly, B is flying upward at an angle θ with repect to the horizontal, and C is flying at the same angle θ as B but downward with respect to the horizontal. Assuming the gournd to be horizontal and neglecting any aerodynamical effect, the speeds v at which the three objects will hit the ground satisfy
vA=vB<vC
vA>vB=vc
vA<vB<vC
vA=vB=vC
5)Two identical conducting spheres, A and B, carry equal electric charge. They are separated by a distance much larger than their diameter and exert an electrostatic force F on each other. A third identical conducting sphere C is initially uncharged and far away from A and B. Sphere C is then brought briefly into contact with sphere A, then with sphere B, and finally removed far away. The electrostatic force between A and B is now