Calculating Momentum of a Spacecraft with Thruster Firing?

[jamiescience]

Homework Statement

a 1.0*10^4kg spacecraft is traveling through space with a speed of 1200 m/s realtive to earth. a thruster fires for 2.0 min, exerting a continuous force of 25kN on the spacecraft in a direction opposite the spacecraft s motion . calculate the initial momentum and the fianl momentum kof the spacecraft .

Homework Equations

The Attempt at a Solution

 

[G01]

You need to show work here in order to get help. Those are the rules. What have you tried so far? What are you thoughts on the problem?

 

[jamiescience]

(-25*10^3)(2.0)=(1.0x10^4)(1200)+(1.0*10^4)(mvi)

 

[G01]

OK. Your big problem is with units. You have seconds on one side of the equation and minutes on the other side of the equation.

Also, remember the equation is:

Impulse =Change in Momentum.
$$J=\Delta p=p_f-p_i$$

Check your signs on the RHS of your equation.

 

[jamiescience]

ok so it would be 120s instead of 2.0min

 

[jamiescience]

(-25*10^3)(120)= (1.0*10^4)(mvi)-(1.0x10^4)(1200)

 

[G01]

(-25*10^3)(120)= (1.0*10^4)(mvi)-(1.0x10^4)(1200)

That looks good to me.