If you wrap some of the wire around the nail in one direction and some of the wire in the other direction, the magnetic fields from the different sections fight each other and cancel out, reducing the strength of your magnet.
The french revolution led to many deaths and impacted history because of the amount of life lost
I'd guess at valve B. more information about the interesting question would help.
Answer:
Explanation:
We need to assume that the density of the concrete is about 2350 Kg/m^3. And using the dimensions of the highway we can calculate the volume of the highway.

Answer:
Da=(1/4)Db
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration due to gravity = 9.81 m/s²
When s = Da, t = t

When s = Db, t = 2t

Dividing the two equations

Hence, Da=(1/4)Db