There's only one question there.
The answer is "Greater amplitude".
Answer:
B = 4.059 x 10¹⁵ T
Explanation:
Given,
Number of loop, N = 400
radius of loop, r = 0.65 x 10⁻¹⁵ m
Current, I = 1.05 x 10⁴ A
Magnetic field at the center of the loop


B = 4.059 x 10¹⁵ T
Answer:

Explanation:
Regardless of the initial velocity of the pebble, the acceleration of the pebble is equal to the gravitational acceleration which is equal to 9.8 m/s2 towards downwards direction.
This can be shown by Newton's Second Law. According to the law, the net force applied on an object is equal to mass times acceleration of that object.
During the downward motion, the only force acting on the pebble is the gravitational force, hence its acceleration is equal to gravitational acceleration.