Mass and distance
force /pull of gravity decreases with the increase in separation between the two bodies
the amount of gravity an object possesses is proportional to the mass of that object.
Answer:
The initial velocity of the ball is <u>39.2 m/s in the upward direction.</u>
Explanation:
Given:
Upward direction is positive. So, downward direction is negative.
Tota time the ball remains in air (t) = 8.0 s
Net displacement of the ball (S) = Final position - Initial position = 0 m
Acceleration of the ball is due to gravity. So,
(Acting down)
Now, let the initial velocity be 'u' m/s.
From Newton's equation of motion, we have:

Plug in the given values and solve for 'u'. This gives,

Therefore, the initial velocity of the ball is 39.2 m/s in the upward direction.
Variables:
Source charge, Q = 3 micro C = 3 * 10^ - 6 C
E = electric field = 2.86 * 10 ^5 N/C
K = 8.99 * 10^9 N * m^2 / C
d = distance = ?
Formula:
E = K * Q / (d^2) => d^2 = K * Q / E
=> d^2 = 8.99 * 10^9 N * m^2 / C * 3 * 10^ -6 C / (2.86 * 10^ 5 N/C)
d^2 = 9.43 * 10 ^ -2 m^2
=> d = 3.07 * 10^-1 m
Answer: 0.307 m
Note: it is a long distance due to the Electric field is very low
Explanation:
When an object moves in a circular path, it will have circular acceleration. Its magnitude of acceleration is given by :

Since, 

T is the time period
R is the radius of the circular path
To increase the centripetal acceleration bu a factor of 1.5 or 3/2, radius of circle must be increase by a factor of 6 and T is increased by a factor of 2 such that,
R'=6R and T'=2T
So,




Hence, this is the required solution.