Answer:

Explanation:
As we know that the magnetic field near the center of solenoid is given as

now we know that initially the length of the solenoid is L = 18 cm and N number of turns are wounded on it
So the magnetic field at the center of the solenoid is 2 mT
now we pulled the coils apart and the length of solenoid is increased as L = 21 cm
so we have

now plug in all values in it


Answer:
18 radians
Explanation:
The computation is shown below:
As we know that
Torque = Force × Moment arm
= 1N × 1M
= 1N-M
Torque = 

Now

Here t = 1 minutes = 60 seconds
Answer:
350.72 m/s
Explanation:
Formula for velocity of wave is;
v = fλ
Where;
v is speed
f is frequency
λ is wavelength
We are given;
f = 512 Hz
λ = 0.685 m
Thus;
v = 512 × 0.685
v = 350.72 m/s
Weight equals mass*gravity
W = mg
Given m = 3.1 kg, g = 9.8 m/s^2
W = (3.1)(9.8)
W = 30.38