Finding Fnet with missing variables

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In summary, the conversation discusses eight model rockets that have just had their engines shut off. The rockets are all aimed straight up and have different speeds and masses. The equation Fnet = ma is used to determine that the net force for all rockets is zero, assuming no air resistance. The conversation also mentions the use of acceleration due to gravity to find the net force, as the rockets are on Earth.
  • #1
CharmedForever
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Homework Statement



The eight figures below depict eight model rockets that have just had their engines shut off. All of the rockets are aimed straight up, but their speeds differ. All of the rockets are the same size and shape, but they carry different loads, so their massed differ. The specific mass and speed for each rocket is given in each figure. (In this situation, we are going to ignore any effect air resistence may have on the rockets.) At that instant when the engines are turned off, the rockets are all at the same height.

Rocket A: 30m/s and 700g
Rocket B: 40 m/s and 500g
Rocket C: 20m/s and 600g
Rocket D: 20m/s and 700g
Rocket E: 30m/s and 400g
Rocket F: 40m/s and 600g
G: 30m/s and 600g
H: 30m/s and 500g

Homework Equations



Fnet= ma

The Attempt at a Solution



The net force for all of them is zero based on the equation Fnet = ma. Because we were told to ignore air resistence, we assume that acceleration is zero for all the rockets and therefore the rockets are traveling at constant velocities. If we input any of the masses into the equation above, the net force for any of the rockets will be zero because the acceleration is zero. Anything times zero is always zero.

*(I desperately need help with this question. My teacher insists that there is way to find the Fnet without time but I don't see how that is possible. Any help would be appreciated. Thanx)*
 
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  • #2
Is this on Earth or in a void? Gravity could be your key.
 
  • #3
It is on earth... How would I use gravity to answer the question... I am really lost here.
 
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  • #4
Then I assume your teacher expects you to use acceleration due to gravity. I'm just a student like you, so take what I say with a grain of salt, but I'm almost certain that's what he expects you to do.
 
  • #5
Alright, thanks so much... I shall try that.
 

1. What is Fnet and why is it important in scientific research?

Fnet, or net force, is the overall force acting on an object. It is important in scientific research because it helps us understand and predict the motion of objects. By knowing the net force, we can determine if an object will accelerate, decelerate, or remain at a constant velocity.

2. How do I find the net force when some variables are missing?

To find the net force when some variables are missing, we can use Newton's second law of motion: Fnet = ma. This means that the net force is equal to the mass of an object multiplied by its acceleration. By rearranging the equation, we can solve for the missing variable.

3. What are the common variables needed to find Fnet?

The common variables needed to find Fnet include mass, acceleration, and the individual forces acting on an object. Other variables that may be needed include velocity, time, and distance.

4. Can you provide an example of finding Fnet with missing variables?

Sure! Let's say we have a mass of 5 kg and an acceleration of 10 m/s^2, but we don't know the individual forces acting on the object. We can use the formula Fnet = ma and plug in the values to find that the net force is 50 N. This means that the sum of all the forces acting on the object must be 50 N.

5. What are some tips for solving problems involving finding Fnet with missing variables?

Some tips for solving these types of problems include carefully reading the question to identify what variables are given and what is being asked, using the correct units for each variable, and rearranging the formula if needed to solve for the missing variable. It can also be helpful to draw a diagram or write out all the known variables to help organize your thoughts.

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