Answer:
When one of charge is doubled, the magnitude of the force between them gets doubled.
Explanation:
The electric force between two electric charges is given by :

Here,
k is the electrostatic force
d is the separation between charges
are charges
If one of the charges is doubled in magnitude while maintaining the same separation between the charges, 
New force becomes,



When one of charge is doubled, the magnitude of the force between them gets doubled. Hence, this is the required solution.
You skipped over a number in the question, and you didn't tell me what my average speed is. Lucky for you, my average speed has NO EFFECT on the answer to the question.
When you calculate velocity, you only use the straight-line distance between the start-point and the end-point. It doesn't matter what route the thing took to get there, or how much ground it actually covered.
If I travel in a circle and stop at the same point I started from, then the size of the circle doesn't matter, and neither does my speed. The distance between my start-point and my end-point is zero, and my average velocity is zero.
Answer:
1.805 mm
Explanation:
Extension in the steel wire = WL_{steel}/AE_{steel}
Extension in the aluminium wire = WL_{Al}/AE_{Al}
Total extension = W/A * (L_{steel}/E_{steel} + L_{Al}/E_{Al})
we have:
W = mg
W = 5 × 9.8
W = 49 N
Area A = π/4 × (0.001)²
= 7.85398 × 10 ⁻⁷ m²
Total extension = W/A * (L_{steel}/E_{steel} + L_{Al}/E_{Al})
Total extension = 49/ 7.85398 × 10 ⁻⁷ ( (1.5/ 200×10⁹) + 1.5/ 70×10⁹))
Total extension = 0.0018048
Total extension = 1.805 mm
Thus, the total extension = the resulting change in the length of this composite wire = 1.805 mm
20waves/57.1s = 0.350 Hz
thank you!