Firework launching question?

Question

Rachels crew is finally sucessful in shooting the firework. They shoot it to its maximum height in 7 seconds and it expoldes sending fragments scattering in horizontal directions all around at a speed of 20 meters per second. In answering the questions below, assume that air drag is negligible.

A. At the end of 7 seconds how far in a horizontal direction will the fragments have scattered.

B. What will be the acceleration of the fragments as they fall vertically.

C. Assuming that they all fall from the same maximum height, how long will it take the fragments to hit the ground.

D. What is the path of the fragments as they fall to the ground.

E. Why do the fragments follow this path.

If anyone knows any of the following answers please let me know. Would be greatly appreciated.

Answer 1

A- assuming no air resistance - if they go horizontally at 20 M/s then 7X20 = 140m

B- Standard value of G 9.8m/s if my memory serves after 30 years out of school

C. hmm, I cant work this one out as you need to work out the maximum height. Maybe if you assume instantaneous acceleration at  the start, like (to a first approximation) a gun or mortar, then the answer will be the same time the projectile took to get to the maximum height.

But- A rocket will accelerate for time X, till it burns out. It will then decelerate at 9.8m/s (assuming a vertical launch/climb)

D- Parabola ( more accurately, each will describe a half parabola.

E- The fragments will travel outwards at a fixed velocity, but downwards at an accelerating velocity.    

Answer 2

Dont look into the tube!