What is the mass of a bird if it has a potential energy of 147J when flying at a height of 30 m above the ground?

0.5kg

Explanation:

Given parameters:

Potential energy = 147J

Height  = 30m

Unknown:

Mass of the bird  = ?

Solution:

Potential energy is the energy due to the position of a body. Now, the expression for finding the potential energy is given as;

      P.E  = mgH

m is the mass

g is the acceleration due to gravity = 9.8m/s²

H is the height

      147  = m x 9.8 x 30

         m = 0.5kg

d.7.5cm is your answer

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.