Alot as far as i know unless you need it in formal terms.
Answer:
6
Explanation:
The magnetic field inside a solenoid is given by the following formula:

where,
B = Magnetic Field Inside Solenoid
μ₀ = permittivity of free space
n = No. of turns per unit length
I = Current Passing through Solenoid
For Solenoid 1:

For Solenoid 2:
n₂ = 6n₁
Therefore,

Diving equation 1 and equation 2:

Hence, the correct option is:
<u>6</u>
Period of months where the weather is the coldest and the days are the shortest.
Impulse = (force) x (time)
The first impulse was (20 N) x (10 sec) = 200 meters/sec
The second one is (50 N) x (time) and we want it equal to the first one, so
(50 N) x (time) = 200 meters/sec
Divide each side by 50N : Time = 200/50 = <em>4 seconds</em>
By the way, the quantity we're playing with here is the cart's <em>momentum</em>.