What is the net force on a weather rocket during its flight?

AI Thread Summary
The discussion revolves around calculating the net force on a weather rocket during its flight, given its velocity, acceleration, and mass loss due to fuel consumption. The key equations mentioned include momentum and Newton's second law, with a focus on differentiating momentum to find force. A participant expresses confusion about applying the correct reasoning and calculations for the problem. Another user provides a hint about using the product rule for differentiation to correctly approach the problem. The conversation emphasizes the importance of understanding the relationship between mass, velocity, and force in the context of changing mass during rocket flight.
bcjochim07
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Homework Statement


A small rocket to gather weather data is launched straight up. Several seconds into the flight, its velocity is 120 m/s and it is accelerating at 18 m/s^2. At this instant, the rocket's mass is 48 kg and it is losing mass at the rate of .5 kg/s as it burns fuel. What is the net force on the rocket? Hint: Newton's second law was presented in a new form in this chapter


Homework Equations


p=mv F=dmv/dt F=dp/dt


The Attempt at a Solution



I tried to come up with a formula for momentum with respect to time and then differentiate it to find force, but it's not making sense to me.

I tried to say that at this instant dm/dt= -.5 and dv/dt = 18 and then I tried to multiply those but that clearly is not correct reasoning. I'm pretty sure I'm not looking at this problem right. Any hints?
 
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Welcome to PF!

bcjochim07 said:
I tried to say that at this instant dm/dt= -.5 and dv/dt = 18 and then I tried to multiply those but that clearly is not correct reasoning. I'm pretty sure I'm not looking at this problem right. Any hints?

Hi bcjochim07 ! Welcome to PF! :smile:

A hint? :rolleyes: … yes! …

Product rule: d(mv)/dt = mdv/dt + vdm/dt. :smile:
 
Oh yes, I see. Thank you very much!
 

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