Note that some of these do not have an explanation. These questions
on a real final will not need an explanation.
 

1) b) current

2) Energy = charge * voltage = 1 C * 6 V = 6 J

3) increase. Thinner wires have more resistance. Longer wires have
more resistance.

4) F1 causes the largest torque because it has the largest moment arm
(perpendicular distance to the axis)

5) positively charged.

6) V = IR = 5 A * 10 Ohm = 50 V

7) P = IV = 2 A * 120 V = 240 W

8) (a) more than the resistance of either lamp. R_total = R1 + R2

9) a) more light. The brightness of the first lamp is unchanged. The
second lamp adds its light to the total.

10) less resistance. Both bulbs use the same voltage. The 100 W bulb
uses more power, therefore uses more current, therefore has less
resistance.

11) e) electron kinetic energy is converted to other forms of energy.
The electrons are not 'used up'.

12) c) The generator converts kinetic energy to electrical energy and
then to light and heat in the light bulb. The more power the bulb
uses, the faster (ie: less time) the kinetic energy of the bicycle
is used up and the faster (ie: less time) it comes to a halt. If
the bulb is burned out, then it does not use any power at all.

Extra solution: This is a conservation of energy problem.  The bicycle
starts with a certain amount of kinetic energy.  When it all gets converted
to other forms of energy, the bicycle will be stopped.  (Because the bicycle
is 'coasting', the bicyclist is not pedaling.)  The generator converts this
kinetic energy to electrical energy.  The more power the lamp uses,
the less time it takes to convert all of the kinetic energy to electrical energy.
The high wattage lamp will cause the bike to stop in the least time.  The low
wattage lamp will cause the bike stop in more time.  If the lamp is burned out
then it uses zero watts and the bike will keep going for much longer.

13) moving electric charge

14) c) perpendicular. The magnetic force is always perpendicular to
both the direction of motion and to the magnetic field. The
charge of the particle is irrelevant.

15) d) other. The force is in the direction of the electric field.
It does not depend on the motion of the particle.

16) a) north pole. The magnet magnetizes the paper clip. It makes a
south pole at the top of the paper clip (where it touches the
north pole of the magnet) and therefore a north pole at the bottom
of the paper clip.

17) d) all of these. All three of these result in a changing magnetic
field at the wire.

18) d) iron rod. Iron amplifies magnetic fields.

19) a) similar devices. A generator is just a motor run backwards.

20) c) power in = power out.

21) e) 1:100. You want 100 times the voltage in the secondary so you
need 100 times more turns in the coils since
(voltage/turns)primary = (voltage/turns)secondary

22) a) a = delta v / t = 30 m/s / 6 s = 5 m/s^2
b) F = ma = 1000 kg * 5 m/s^2 = 5000 N
c) KE = 1/2 mv^2 = 1/2 (1000 kg) (30 m/s)^2 = 450,000 J = 4.5*10^5 J
d) power = KE/time = 4.5*10^5 J / 6 s = 7.5*10^4 W (= approx 100 horsepower)

23) a) positively charged. The rod polarizes the can so the near side
is positively charged and the far side is negatively charged.
When you touch the far side, you allow the electrons to leave the
can, leaving it positively charged.

24) The athlete starts with KE = 1/2 mv^2 = 1/2 * 70 kg * (10 m/s)^2
so KE = 3500 J. If this is all converted to PE, then
PE = mgh = 3500 J or h = 3500 J / mg = 3500 J / (70 kg * 10 m/s^2)
so that h = 5 m.

25) c) the same. Newton's third law.

26) The linear speed of a point on the outside of the tire is 30 m/s.
Therefore the rotational speed is

v_rotational = 30 m/s / (2pi r) = 30 m/s / (3.14*0.8 m)
= 12 rotations / second

27) d) zero. The part of the tire touching the ground is not moving.
If the part of the tire touching the ground is moving, it is
called a 'skid' and you would not like it at all.

28) e) need more info. You can reduce the momentum by either going
slower (reducing v) or dumping cargo (reducing m). If v is
quartered, then KE decreases by a factor of 16 (since KE ~ v^2).
If m is quartered, then KE decreases by a factor of 4. Therefore,
we do not know how much the KE changes.

29) e) need more info. We know the momentum change but we need
the time over which the force was applied to determine the force.
The player's mass is utterly irrelevant.

30) a) attract. Opposite charges attract.

31) b) 10 m/s^2. g is g. Objects in free fall accelerate downward at
10 m/s^2 regardless of whether they are moving quickly upward,
not moving or moving quickly downward.

32) b) object B has the greater acceleration. a = F/m. The force is
the same for both. Object B has a smaller mass (1 kg instead of 5
kg) so it has a larger acceleration. The charges of the objects
are irrelevant.

33) a) A has the larger rotational inertia because the masses are
farther from the acis.

34) b) both. It has little charge and therefore not that much
energy. We know it has little charge because people are not
killed by rubbing balloons on their clothing. We know it has
little energy since we cannot feel the spark when it discharges
(as opposed to the other shocks we get in the winter that have
little charge but significant energy [ouch!]).

35) c) unchanged. If you change the distance, you will change the
electric and gravitational forces by the same amount since both
are proportional to 1/d^2.

36) attract

37) e) quadruples. F ~ 1/d^2.

38) b) when you polarize an object, you separate its charges so one
side is more negative and the other side is more positive.