Aball is thrown with a horizontal velocity of 80 m/s from the top of a 250 m high building. how long will it be in the air?

19.0 s

Explanation:

Since the motion of the ball is a free-fall motion, we can solve the problem by using the following suvat equation:

where, chosing upward as positive  direction, we have:

s = -250 m is the displacement of the ball to reach the ground

u = +80 m/s is the initial velocity of the ball

t is the time

is the acceleration of gravity

Re-writing the formula we have:

This is a second-order equation, so we solve it by applying the usual formula to find t:

And considering only the positive solution, from the calculation we get

t  = 19.0 s

So, the ball will be in air for 19.0 s.

reserve is the answer

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.