Kinematics problem, don't know how to find unknown variables

In summary, the conversation discusses a problem involving a rocket being shot straight up with an initial speed of 500 m/s. The equations provided by the teacher are Yf = 1/2 A(T)^2 + Vi(T) + Yi and Vf = A(T) + Vi. The attempt at a solution includes the equations Vf = (-9.8)(T) + 500 m/s and Yf = 4.9T2 + 500T + 0, but the unknown variables still need to be solved for. The question is to find all the variables in the equations given.
  • #1
Physicsnoob10
2
0

Homework Statement


A rocket is shot straight up with an initial speed at 500 m/s.


Homework Equations


The equations the teacher went over beforehand were

Yf = 1/2 A(T)^2 + Vi(T) + Yi
Vf = A(T) + Vi

The Attempt at a Solution


So far I have

Vf = (-9.8)(T) + 500 m/s
Yf = 4.9T2 + 500T + 0

...and I have no idea how to go about solving for the rest of the unknown variables. It seems like I need T somehow, but I don't know how I can get it from the information given.
 
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  • #2
What is the question?
 
  • #3
Oh, sorry. Guess I didn't make that clear. You basically just have to find all the variables in the equations.
 
  • #4
I still do not know what is the question.
If you have a rocket with velocity of 500m/s, you can be anywhere in this universe.
Maybe on any planet.
 
  • #5


As a scientist, it is important to approach problems systematically and use the equations and principles that you have learned to solve them. In this case, we are dealing with a kinematics problem, which involves the study of motion and its causes. In order to solve this problem, we need to use the equations of motion that have been provided and apply them to the given information.

First, let's identify the known variables in this problem. We are given the initial speed, Vi, which is 500 m/s. We also know that the acceleration, a, is -9.8 m/s^2 (since the rocket is moving in the opposite direction of gravity). We are trying to find the final velocity, Vf, and the time, T, it takes for the rocket to reach its maximum height.

Using the equation Vf = Vi + at, we can solve for Vf by plugging in the known values: Vf = 500 m/s + (-9.8 m/s^2)(T). This gives us an equation with one unknown variable, T.

Next, we can use the equation Yf = Yi + Vit + 1/2at^2 to solve for T. Since we know that at the maximum height, the final velocity is 0 m/s, we can set Vf = 0 and solve for T. This will give us the time it takes for the rocket to reach its maximum height.

Once we have the value for T, we can use it to solve for the final height, Yf, by plugging it into the equation Yf = 4.9T^2 + 500T + 0.

In summary, to solve this kinematics problem, we need to use the equations of motion and the known variables to systematically solve for the unknown variables. It is important to carefully read and understand the problem and use the appropriate equations and principles to arrive at a solution. With practice and a thorough understanding of the concepts, you will be able to solve more complex problems in the future.
 

1. How do I determine the unknown variables in a kinematics problem?

The first step in solving a kinematics problem is to identify all known variables, such as initial and final positions, velocities, and accelerations. Then, use the appropriate equations of motion to solve for the unknown variables. It may also be helpful to draw a diagram and label all given information.

2. What are the equations of motion for kinematics problems?

The four equations of motion are:
1. v = u + at (relates initial velocity u, final velocity v, acceleration a, and time t)
2. s = ut + 1/2at^2 (relates initial position u, displacement s, acceleration a, and time t)
3. v^2 = u^2 + 2as (relates initial and final velocities, acceleration, and displacement)
4. s = (u + v)t/2 (relates initial and final velocities, time, and displacement)

3. Is there a specific order in which I should solve for unknown variables?

There is no specific order in which you should solve for unknown variables. However, it may be helpful to start with equations that only involve one unknown variable and work your way up to more complex equations with multiple unknowns.

4. What should I do if I have more unknown variables than equations?

If you have more unknown variables than equations, you will not be able to solve for all of them. In this case, you may need to rearrange the equations or use additional information given in the problem to solve for the remaining unknowns. It may also be helpful to make assumptions or estimates for certain variables.

5. Can I use the same equations of motion for all kinematics problems?

Yes, the equations of motion can be used to solve for unknown variables in any kinematics problem, as long as the problem involves constant acceleration. However, for problems with non-constant acceleration, such as free fall, different equations may need to be used.

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