Projectile Motion given a vertical distance and angle at that point

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The discussion revolves around solving a projectile motion problem involving a projectile at a height of 10m and an angle of 45 degrees. Key points include recognizing that the horizontal and vertical components of velocity (Vx and Vy) are equal at this angle, which is crucial for solving the problem. Participants discuss the absence of acceleration in the x-direction and the presence of acceleration due to gravity in the y-direction. The equations of motion, referred to as the "Famous Five," are suggested as tools to derive further information. Ultimately, the original poster successfully resolves their confusion and finds a solution.
whoareyou
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Homework Statement


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Homework Equations


Famous Five equations for uniform accelerated motion

The Attempt at a Solution


To be honest, I have absolutely no idea where to start. The only thing that I notice is that at the point where you're given the velocity vector (when the projectile is 10m above the ground) it makes an angle of 45 degrees, which means that both vx and vy are equal. I don't really know where to go from there.
 
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whoareyou said:
To be honest, I have absolutely no idea where to start. The only thing that I notice is that at the point where you're given the velocity vector (when the projectile is 10m above the ground) it makes an angle of 45 degrees, which means that both vx and vy are equal. I don't really know where to go from there.

I'm glad you recognize Vx and Vy are equal. That is key to being able to solve the problem. :smile:

Since you know Vx and Vy are equal, think about what else you know.
What is the acceleration in the x-direction?
What about in the y-direction?

Knowing the starting position (just clearing the wall) can you use any of those "Famous Five" with Vx and Vy and your known accelerations to set up an expression that will let you solve for more information?
 
There is no acceleration in the x direction, delta d x = vx delta t.
There is acceleration in the y direction, delta d = viy delta t + 1/2 g delta t squared

delta d y = delta d x x time + 1/2 g t squared --> i end up with -18 = 4.9t^2 which can't be done.
 
NVM! got it YAY!
 
whoareyou said:
NVM! got it YAY!

Alright then. Glad to hear it. :approve:
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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