Projectile Motion -- mountain jumper

AI Thread Summary
The discussion revolves around a physics problem involving projectile motion where a jumper runs off a 910-meter mountain at a speed of 4.0 m/s and free falls until reaching 150 meters above the valley floor before opening her parachute. Key questions include determining the duration of free fall and the horizontal distance traveled when the parachute opens. The vertical component of the motion is clarified, indicating that the initial height should be considered as 760 meters (910m - 150m) for calculations. The jumper's initial vertical velocity is zero, and the acceleration due to gravity is -9.8 m/s². The participant seeks clarification on the vertical component to correctly apply kinematic equations for solving the problem.
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1. Homework Statement
A jumper runs horizontally off a 910 meter mountain with speed 4.0 m/s and enjoys a free fall until she is 150 meters above the valley floor, at which time she opens her parachute. Ignore air resistance

Homework Equations


A) how long is the jumper in free fall.

B) how far from the cliff is the jumper when she opens her parachute?

The Attempt at a Solution


My attempt is attached with kinematic equations. I want to use Y to find time.

I'm confused on Y. Is it the height 910 meters or 910 meters - 150 meters = 760 meters. Can you explain the vertical component to me?
 

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In the case of Y = y_0 + v_0t + 1/2*at^2, your Y at the time you are interested in should be Y at the end of the free fall, or 150m.
y_0 is the starting height, v_0 is the vertical component of initial velocity (zero) and a should be -9.8m/s^2.
 
Thank you RUber. I am about to rework it.
 
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