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.

When many atoms are split in a chain reaction, a large explosion occurs. this is an example of what type of energy conservation

Askydiver weighing 140 lb (including equipment) falls vertically downward from an altitude of 19,000 ft and opens the parachute after 18 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.55|v| when the parachute is closed and is of magnitude 14|v| when the parachute is open, where the velocity v is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. (a) find the speed of the skydiver when the parachute opens. (b) find the distance fallen before the parachute opens. (c) what is the limiting velocity vl after the parachute opens? (d) determine how long the sky diver is in the air after the parachute opens. (e) plot the graph of velocity versus time from the beginning of the fall until the skydiver reaches the ground.

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final