Distance traveled and hang time for 2D projectile

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SUMMARY

The discussion centers on calculating the hang time and distance traveled by a cannonball fired from a height of 0.43 meters at angles of 42 degrees and 35 degrees. The initial calculations yielded a muzzle velocity of 8.85 m/s, with horizontal and vertical components determined using trigonometric functions. The analysis revealed that the cannonball lands 3 meters below the muzzle level, indicating a discrepancy in the assumptions about the ground level or cannon height. The participants are tasked with recalculating the hang time and distance for the 35-degree angle based on these findings.

PREREQUISITES
  • Understanding of projectile motion principles
  • Familiarity with trigonometric functions (sine and cosine)
  • Knowledge of kinematic equations for vertical motion
  • Basic grasp of vector decomposition
NEXT STEPS
  • Calculate the hang time and distance for a 35-degree launch angle using the derived muzzle velocity.
  • Explore the effects of varying launch angles on projectile motion.
  • Investigate the impact of initial height on projectile trajectories.
  • Review the principles of conservation of energy in projectile motion.
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Students studying physics, particularly those focusing on mechanics and projectile motion, as well as educators seeking to clarify concepts related to angles, velocities, and kinematics.

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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?
 

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