How Does Thrust Affect the Weight Calculation of a Spacecraft on Planet X?

In summary: Planet X. The spacecraft's engines produce a 25.0kN thrust, which slows the spacecraft down at a rate of 1.20m/s^2. If an upward thrust of only 10.0kN is applied, the spacecraft speeds up at a rate of .80m/s^2.Newton's second law states that the net force on an object is the product of its mass and its acceleration. When applying Newton's second law to the situation of the spacecraft slowing down due to the 25.0kN thrust and then speeding up when the 10.0kN thrust is applied, the mass of the spacecraft near the surface of Planet X can be found
  • #1
Peach
80
0

Homework Statement


A spacecraft descends vertically near the surface of Planet X. An upward thrust of 25.0kN from its engines slows it down at a rate of 1.20m/s^2, but if an upward thrust of only 10.0kN is applied, it speeds it up at a rate of .80m/s^2. Apply Newton's second law to each case, speeding up or slowing down, and use this to find the spacecraft 's weight near the surface of Planet X.


Homework Equations


F = ma


The Attempt at a Solution


Okay, I'm confused about how if 25.0kN force is applied, then it slows down but 10.0kN part will speed it up. I guess maybe that's why my method is wrong and I keep getting the wrong answer. This is what I'm doing: since I have the force and acceleration, I converted kN to N and divided by its acceleration to find the mass. Then I take the mass x gravity = weight, converting it back kN. Pls help me, where did I go wrong?
 
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  • #2
Another poorly worded problem if that's quoted accurately. Is the right answers 2.13(7500)=15975?
 
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  • #3
Yeah, I copied it word for word. I don't have the right answer but um, how did you get those numbers?
 
  • #4
well what the question supposes(and its poorly worded) is "it" is the planets gravitational pull. In one case it retards the spacecraft s upwards acceleration so that the net acceleration is up, and in the second case the gravitational pull overcomes the thrust of the rocket. In each case, try to develop an eqn for the given net a in terms of the rocket thrust and unknown g constant of the planet. Should have 2 eqns, 2 unknowns.
 
  • #5
Ah, if you didn't explain, I don't think I'd understand the problem...I got it now, thank you very much.
 
  • #6
My pleasure, I just can't resist a rocket problem!
John
 

FAQ: How Does Thrust Affect the Weight Calculation of a Spacecraft on Planet X?

What is force?

Force is a physical quantity that describes the interaction between two objects. It is measured in Newtons (N) and is represented by the symbol F.

What is acceleration?

Acceleration is the rate of change of an object's velocity over time. It is measured in meters per second squared (m/s²) and is represented by the symbol a.

What is weight?

Weight is a measurement of the force of gravity acting on an object. It is measured in Newtons (N) and is represented by the symbol W.

How are force, acceleration, and weight related?

According to Newton's second law of motion, force is equal to an object's mass multiplied by its acceleration. This means that the greater the force applied to an object, the greater its acceleration will be. Weight is simply a type of force that is affected by the acceleration due to gravity.

How do you calculate force, acceleration, and weight?

Force can be calculated using the formula F = m x a, where m is the mass of the object and a is the acceleration. Acceleration can be calculated using the formula a = (vf - vi)/t, where vf is the final velocity, vi is the initial velocity, and t is the time. Weight can be calculated using the formula W = m x g, where m is the mass of the object and g is the acceleration due to gravity (9.8 m/s² on Earth).

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