Students want to build a simple motor to demonstrate the relationship between magnetism and electricity. Each student group has a wooden block, paper clips, a battery, and some copper wire. What additional material is necessary to build a
simple motor?
A An iron nail is necessary to produce a temporary magnetic field.
B. A magnet is necessary to produce a permanent magnetic field.
C. An iron nail is necessary to act as the electrical circuit load.
D. A magnet is necessary to act as the electrical circuit load.

In the middle of the night you are standing a horizontal distance of 14.0 m from the high fence that surrounds the estate of your rich uncle. the top of the fence is 5.00 m above the ground. you have taped an important message to a rock that you want to throw over the fence. the ground is level, and the width of the fence is small enough to be ignored. you throw the rock from a height of 1.60 m above the ground and at an angle of 54.0 degrees above the horizontal. part a part complete what minimum initial speed must the rock have as it leaves your hand to clear the top of the fence? express your answer with the appropriate units. part b for the initial velocity calculated in the previous part, what horizontal distance beyond the fence will the rock land on the ground?