The maximum height of the projectile is the maximum point that can be gotten from the projectile equation
The projectile reaches the maximum height after 5 seconds
The function is given as:

Differentiate the function with respect to t

Set to 0

So, we have:

Collect like terms


Solve for t


Hence, the projectile reaches the maximum after 5 seconds
Read more about maximum values at:
brainly.com/question/6636648
To determine the answer of Part A draw the equilateral triangle and the to determine the coordinates of of the third charge use that triangle.
To calculate the gravitational field strength in part B from each of the charges use the following equation.
E=kcq/r2
If you would add those values then you can use the symmetry about the y axis to make the vector addition a litter easier.<span />
answer
.618 18 repeats
Step-by-step explanation:
1=51
2=34
3= 95 (i think)
4=38