A. because it's been repeated multiple times
Answer:
204 m
Explanation:
When the marble is dropped from a certain height, its gravitational potential energy converts into kinetic energy. So the kinetic energy gained is equal to the variation of gravitational potential energy:

where
m is the mass of the marble
g = 9.8 m/s^2 is the acceleration of gravity
is the change in height
In this problem, we have
m = 50 g = 0.05 kg

Solving the formula for
, we find the necessary height from which the marble should be dropped:

Answer:
D, the acceleration of A is twice that of b.
Explanation: in four seconds b got to ten, in two seconds a got to 20. Going 10m/s faster in half the time is going twice the acceleration
Ampere per meter squared A/m