Distance traveled and hang time for 2D projectile

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The discussion centers on a physics problem involving projectile motion from a cannon fired at an angle of 42 degrees, with a horizontal distance of 8.9 meters and a hang time of 1.5 seconds. The user attempts to calculate the muzzle velocity and the vertical and horizontal components of the velocity using trigonometric functions but encounters confusion regarding the cannonball's landing height. Calculations indicate that the cannonball lands approximately 3 meters below the cannon's height of 0.43 meters, suggesting a potential issue with the ground's flatness or the cannon's height. The user seeks clarification on the conflicting information and the correct approach to solve for hang time and distance when the cannon is fired at a different angle of 35 degrees. Overall, the discussion highlights the complexities of projectile motion calculations and the importance of accurate initial conditions.
Kstan333
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Homework Statement



A cannon is fired at an angle of 42 degrees, the cannon ball travels 8.9 meters in the x direction. Its hang time is 1.5 seconds. The cannon site .43 meters above the ground on a stand. If this same cannon was fired at 35 degrees, what would the hang time and the distance traveled be?

Homework Equations





The Attempt at a Solution


I tried to use velocity vectors and find the speed at which the cannon ball was fired, muzzle velocity, using A^2+B^2=C^2. Giving me a velocity of 8.85m/s, using this I attempted to use sine and cosine to find the velocitys in the x and y direction. I am stuck here.
 
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Must be something I'm not understanding. There seems to be too much information, and it conflicts. From the hang time (= time in the air, yes?) and the horizontal distance I can calculate horizontal speed. From that and the launch angle I can compute vertical speed at muzzle. From that, the hang time, and taking g=9.81 m/s2 I compute that the cannonball lands 3.02 m below the level of the muzzle, but we're told the cannon is only .43 m above the ground.
 
I agree...

Vx = 8.9/1.5 = 5.933 m/s
Then..
Vx = V Cos(42)
V = 7.984 m/s

Vy = V Sin(42)
= 5.342 m/s

Vertically
S=ut-0.5at2
S=5.342 * 1.5 - 0.5*9.8*1.52

= 8.013 - 11.025
=-3m

So it does appear to land 3m below the cannon. So perhaps the ground isn't flat?

Perhaps an error in the height of the cannon?
 
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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