Standing at the top of a 30.0 m high cliff, you throw a rock straight down with a velocity of 8.00 m/s. after how many seconds does it hit the ground?

It will take 1.789 sec  

Explanation:

We have given height h = 30 m

Initial velocity u = 8 m/SEC

Acceleration due to gravity

Now according to second equation of motion

After solving we get t = -3.42 sec and t = 1.789 sec

As negative time is not possible so time will be 1.789 sec

like poles repel so keep pushing north to north and repels funny to see this

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.