Question concerning initial velocity

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Homework Help Overview

The problem involves calculating the take-off speed of an athlete executing a long jump, given the angle of take-off and the distance traveled. The subject area pertains to kinematics and projectile motion.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to derive a formula for distance based on initial velocity and angle but questions the correctness of their approach. Some participants clarify the correct formula to use, while others suggest alternative methods involving the vertical and horizontal components of motion.

Discussion Status

Participants are actively discussing different formulas and approaches to the problem. There is recognition of potential algebraic errors in the original poster's derivation, and some guidance has been provided regarding the correct formula to apply.

Contextual Notes

The discussion highlights the importance of careful algebraic manipulation and the need to ensure the correct application of kinematic equations in projectile motion scenarios.

Casimi
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Homework Statement



An athlete executing a long jump leaves the ground at a 31.6° angle and travels 7.78 m. What was the take-off speed?

I have tried to solve this question but somehow keep arriving at the wrong answer. The formula that I derived is :

distance=V(initial)*sin^2(theta)/g

Where am I going wrong here? Any help would be appreciated.
 
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Are you computing

distance=V0sin2θ/g

OR

Distance = V02sin2θ/g?

The second one is the one should use.
 
It seems as if I derived the wrong formula via a mistake in my algebra.

Thank you so much!
 
i get a different formula for it.

First take the vertical component, and find the total time taken. Now take the horizontal component of the velocity and multiply by time to find the expression for distance(range)

Substitute and get your answerEDIT: rock.freak answered first, i guess...
 
It seems like I should take more time to organize my thoughts and perform my algebra correctly. Simple mistakes are always my downfall!
 

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