Arocket is dropped out of an airplane at 100 m/s (downward). if the rocket fires causing an upward acceleration of ct2 and it takes 20 seconds to reach zero velocity, what is the value of c?

C = 0.0125 m/s⁴. The calculation procedure can be found in the attachment below. The concept of motion along a straight line with constant acceleration has been applied to solve the problem.

Explanation:

The sign convention chosen in this problem solution is upwards as positive and downwards negative. The equation of motion v = u + at has been used to calculate the constant C as only one unknown is contained in this equation. This is so because we have been given the initial velocity, the acceleration and the time taken. To solve future problems of this kind, first thing to check for is an equation of motion with the least number of unknown. This helps to reduce the complexity of the problem solution.  

it should be -8.6 cm hope this out

pe = weightxheight = 2000x1000=2,000,000joules