Solve Kinematics: Find Vi of Flea Jumping 0.390m

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SUMMARY

The problem involves calculating the initial velocity (Vi) of a flea jumping to a maximum height of 0.390m using the kinematic equation vf² = vi² + 2ad. The correct approach requires recognizing that the acceleration due to gravity (a) is -9.8 m/s², which is negative because it acts in the opposite direction to the jump. By correctly applying the equation and understanding the vector directions, one can solve for Vi without encountering negative values.

PREREQUISITES
  • Understanding of kinematic equations, specifically vf² = vi² + 2ad
  • Knowledge of vector direction in physics
  • Familiarity with the concept of acceleration due to gravity
  • Basic algebra skills for solving equations
NEXT STEPS
  • Study the application of kinematic equations in vertical motion problems
  • Learn about vector components and their significance in physics
  • Explore the effects of gravity on projectile motion
  • Practice solving similar problems involving initial velocity and maximum height
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Students studying physics, educators teaching kinematics, and anyone interested in understanding the principles of motion and acceleration in vertical jumps.

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A flea jmps to a maximum height of 0.390m. Find vi as it leaves the ground.

I thought of using the equation vf^2 = vi^2 + 2ad
but in this case, if i want to find out vi, I get
-vi^2 = 2ad.
and because of the negative, it doesn't work...

How do you solve this problem??
 
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jnimagine said:
A flea jmps to a maximum height of 0.390m. Find vi as it leaves the ground.

I thought of using the equation vf^2 = vi^2 + 2ad
but in this case, if i want to find out vi, I get
-vi^2 = 2ad.
and because of the negative, it doesn't work...

How do you solve this problem??

Acceleration due to gravity: a = -9.8m/s2 note the minus sign!

The reason why this is negative: the flea is jumping up (positive direction), acceleration is acting down (negative direction as it is opposite to the direction of the jump)

This cancels out your problem of negative displacement when you realize you are working with vectors that have different directions.
 

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