- #1
amiras
- 65
- 0
For example then talking about the rocket the trust is:
F_thrust = u*dm/dt
where u is speed of the gases relative to the rocket, and dm/dt rate of change of ejected mass of gases.
Now if the rocket is being launched vertically so force of gravity acts upon it and:
F_net = F_thrust - mg = u*dm/dt - mg
According to the 2nd Newton's law:
F_net = dp/dt = v*dm/dt + m*dv/dt = v*dm/dt + ma
If comparing these equations:
ma=-mg in this case:
should that be interpreted that the acceleration a is caused by the forces other then thrust.
And is it possible to write:
F_net = m*dv/dt + F_other = F_thrust + F_other
F_thrust = u*dm/dt
where u is speed of the gases relative to the rocket, and dm/dt rate of change of ejected mass of gases.
Now if the rocket is being launched vertically so force of gravity acts upon it and:
F_net = F_thrust - mg = u*dm/dt - mg
According to the 2nd Newton's law:
F_net = dp/dt = v*dm/dt + m*dv/dt = v*dm/dt + ma
If comparing these equations:
ma=-mg in this case:
should that be interpreted that the acceleration a is caused by the forces other then thrust.
And is it possible to write:
F_net = m*dv/dt + F_other = F_thrust + F_other