<em>the devices which are used to change the resistance in a circuit are called
<u>resisitors...
</u>the fact that they effect the voltage or not simply depends upon the type of resistor used in the circuit ...:)
</em>
a) Answer;
= 6.72 hours
Explanation and solution;
velocity = distance over time
Since we know the velocity and the distance, we can simply calculate time
For the first part
85 km/h = 300km / time
time = 3.53 hours
Then there is a 22 min stop, which is the same as 0.37 hours
so far the trip is:
3.53 + 0.37 = 3.9 hours
then for the last stretch:
78 km/h = 220 km / time
time = 2.82 hours
So the total trip is:
3.9 + 2.82 = 6.72 hours
b) Answer;
= 77.38 km/hr
Explanation and solution;
we take the total distance divided by the total time to get the average.
total distance = 300 km + 220 km = 520 km
total time = 6.72 hours
Average velocity = 520 km / 6.72 hours = 77.38 km/hr
2) b) The height above the surface of the earth
3) b) air pressure differences that make air rise or sink
4) a) TC (I'm not sure about this)
5) I don't know this one. Sorry :(
6) a) true
7) a) true
8) b) false (I'm not sure about this)
Sorry I couldn't answer all your questions, but I hope this helps!
Answer:
The second law of a vibrating string states that for a transverse vibration in a stretched string, the frequency is directly proportional to the square root of the string's tension, when the vibrating string's mass per unit length and the vibrating length are kept constant
The law can be expressed mathematically as follows;

The second law of the vibrating string can be verified directly, however, the third law of the vibrating string states that frequency is inversely proportional to the square root of the mass per unit length cannot be directly verified due to the lack of continuous variation in both the frequency, 'f', and the mass, 'm', simultaneously
Therefore, the law is verified indirectly, by rearranging the above equation as follows;

From which it can be shown that the following relation holds with the limits of error in the experiment
m₁·l₁² = m₂·l₂² = m₃·l₃² = m₄·l₄² = m₅·l₅²
Explanation:
<span>Velocity tells you what speed a moving object travels at and in what direction.</span>