in the structure of an atom why are protons present in the centre and are not pulled outside by the electrons as both are positively charged with some unit of charge?

Electrons and protons are not positively charged

Explanation:

Neutrons are the only ones positively charged in the structure of an atom Also like charges repel which means a -ive and a - ive will repel when together

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

idk what the question is about