Conservation of momentum problem regarding a missing mass of a ship

AI Thread Summary
The discussion centers on a conservation of momentum problem involving an astronaut escaping a malfunctioning spacecraft. The astronaut and escape pod have a combined mass of 1270 kg, with the pod moving at 34.9 m/s and the ship at 1.89 cm/s in the opposite direction. Participants clarify that the initial velocities of both the ship and pod were zero before the explosion, allowing for the application of momentum conservation principles. The key takeaway is that the momentum before and after the explosion must balance, leading to the conclusion that the spacecraft's mass can be determined using the final velocities provided. The conversation emphasizes understanding the relationship between mass and velocity in momentum calculations.
MichaelDunlevy
Messages
6
Reaction score
0

Homework Statement



After a malfunction, an astronaut escapes from a doomed spacecraft by using an escape pod that is blown off of the ship. The small explosion sends the pod flying away at 34.9 m/s, while the main ship moves in the opposite direction at the speed of 1.89 cm/s. If the combined mass of the astronaut and pod is 1270 kg, what is the mass of the doomed spacecraft ?

Homework Equations



Conservation of Momentum:

m1u1+m2u2 (initial) = m1v1+m2v2 (final)



The Attempt at a Solution



I believe that conservation of momentum is the correct principle to use here, but I am unsure how to solve for the spaceship's mass because of the missing initial velocity. Could someone help me out? Thanks!
 
Physics news on Phys.org
Hi there!

The initial velocity was meant to be 0 for both the ship and the pod.
Those velocities provided are for after the separation, relative to their mutual centre of mass.
 
If the spaceship and pod before the launch had 0 momentum to their mutual centre of mass, the conservation of momentum says:

the pod and spaceship must have right after the launch 0 momentum to their mutual centre of mass. So you have 4 variables ( as intial velocities were both 0 ) after the launch; ( mass and velocity of spaceship and pod ).
 
thank you! i figured that the velocity must have been an unknown constant (which would be ridiculous) or 0. I just wanted verification. Thank you for the fast reply guys!
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top