- #1
David Donald
- 31
- 0
Homework Statement
A 25 kg Rocket generates 400 N of thrust. It is designed to burn its fuel for
40 seconds. If launched vertically what will its final vertical velocity be when the fuel runs out? How high can it fly? How long until it reaches the ground? Neglect mass of fuel, and air resistance.
Please check over my work I feel like I may be making a mistake somewhere
Homework Equations
Kinematics Equations
The Attempt at a Solution
First I summed the forces in the Y direction
ΣFy = Ft - Fg = ma
= (400N - 245N)/(25kg) = a = 6.2 m/s^2
Final Vertical Velocity
Vfy = Voy + at
Vfy = 6.2 m/s^2 * 40s = 248 m/s
(Height when fuel runs out)
Yf = Yo + Voy*t + (1/2)a t^2
Yf = (1/2)*(6.2 m/s^2) (40)^2 = 4960 meters
(FINAL HEIGHT)
Vfy = Voy + at
0 = 248 m/s - 9.8m/s^2 t = 25.31 seconds <---- Time of Final Height
Yf = Yo + Voy*t + (1/2)at^2
Yf = 4960m + 248 m/s * 25.31 s = 11385.7 meters
(How Long until it reaches the ground)
I'm confused how to solve this part...