How much energy is stored by the electric field between two square plates, 8.1 cm on a side, separated by a 1.9-mm air gap? The charges on the plates are equal and opposite and of magnitude 17 nC . Express your answer using two significant figures and include the appropriate units.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Explain what it means to view something from a frame of reference. provide an example that illustrates your explanation. (4 points)

Does the distance travelled by an oscillating mass between times t=0 and t2 equal the displacement of the particle over the same time period if t2> t/2? hint: consider a sine wave starting at t1=0, then consider a closing wave starting at t1=0, for your explanation.