1. identify each of the following as conductors or insulators.

19. cloth

20. dry wood

21. tap water

22. glass

2. light passes from air into water at an angle of 40.0° to the normal. what is the angle of refraction? show all work.

3. a rubber rod can be charged negatively when it is rubbed with wool. what happens to the charge of the wool?

4. what is electrical power in terms of current and potential difference?

5. generate an explanation for the following formula: p = i2r

6. three 15.0-w resistors are connected in parallel across a 30.0-v battery. show all work.

a) find the current through each branch of the circuit.

b) find the equivalent resistance of the circuit.

c) find the current through the battery.

7. what happens to the polarity of an electromagnet when the direction of the current passing through it is reversed?

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

the answer is 100. i just did this lesson and got a 100% on it. : )

-fishtank