Projectile Motion, only given horizontal distance

In summary, the conversation is discussing how to calculate the initial speed of a football thrown in a straight line without air resistance effects. The longest pass in history is 85.8m, and using the equations Vx=Vo cosΘ and x=VcosΘt, the initial speed can be determined by assuming an angle of 45 degrees.
  • #1
PhysicsMan999
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0

Homework Statement


The longest pass in history is 85.8m. Ignoring any air resistance effects, calculate the initial speed of football.

Homework Equations


Vx=Vo cosΘ
x=VcosΘt
Vy=VosinΘ -gt
y= VosinΘt - 0.5gt^2

The Attempt at a Solution


I really don't know what to do here. I've looked through all my notes and book and haven't seen any problems like this (with no angle). Every time I try to rearrange and substitute equations I still end up with 2 unknowns. It would be great if someone could point me in the right direction.[/B]
 
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  • #2
Are you sure 85.8m is all you're given? There will be many answers if you only have 85.8m as the distance because the magnitude of the initial velocity will be dependent on the angle. In this case, I'd first ask your teacher and if not, just choose a random angle 90>x>0 (most likely 45 degrees for simplicity).
 
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  • #3
Yeah that's all the question had. You might be right about that, the "longest pass in history" could be implying a 45 degree angle since I remember him saying that a 45 angle would give the greatest range. It would have been nice for him to actually state that in the question though. I'll try to work it out tomorrow (it's 1 AM and I've been pondering it for far too long tonight) like that and see how it goes. Thanks for the help!
 
  • #4
Np, good night.
 
  • #5
Well I managed to work it out, you were right! I assumed an angle of 45 degrees and got the right answer pretty quickly after that using the range formula. Really appreciate the guidance!
 
  • #6
Yep I would assume that assuming 45 degrees would be the best way to approach the problem. Given the way its worded though, it would be a bit confusing.
 

1. What is projectile motion?

Projectile motion is the motion of an object through the air that is affected by gravity. This type of motion follows a curved path, known as a parabola.

2. How is horizontal distance related to projectile motion?

Horizontal distance is the distance traveled by a projectile in the horizontal direction. It is related to projectile motion because the horizontal component of the projectile's velocity remains constant throughout its motion.

3. What factors affect the horizontal distance of a projectile?

The horizontal distance of a projectile is affected by the initial velocity, the angle of launch, and the presence of air resistance. The higher the initial velocity and the smaller the angle of launch, the farther the horizontal distance will be. Air resistance can also decrease the horizontal distance.

4. How do you calculate the horizontal distance of a projectile?

The horizontal distance of a projectile can be calculated using the formula:
d = v * t * cos(theta)
where d is the horizontal distance, v is the initial velocity, t is the time of flight, and theta is the angle of launch.

5. Can the horizontal distance of a projectile ever be infinite?

No, the horizontal distance of a projectile can never be infinite. This is because the effect of gravity will always cause the projectile to eventually fall back to the ground. However, the horizontal distance can be very large depending on the initial velocity and angle of launch.

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