The motion of a skateboarder along and above a ramp

AI Thread Summary
The discussion revolves around the motion of a skateboarder on a ramp, focusing on calculating velocities and understanding energy conservation. The skateboarder starts with a speed of 7.2 m/s and experiences a deceleration of -6.1 m/s² before reaching a height of 1.2 m at event E2. There is confusion regarding the maximum height reached (E3) at a speed of 4.1 m/s and whether mechanical energy is conserved up to that point. The lack of an angle complicates the use of projectile motion formulas, leading to a suggestion to utilize energy equations instead. Clarification on the skateboarder's direction at maximum height and the need for a diagram are also highlighted.
StrugglingStudent123
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Homework Statement
A skateboarder starts at the bottom of a ramp (E1) with a speed of 7.2 m/s. She rolls up the ramp, slowing down with an acceleration of -6.1 m/s², and finally leaves the end of the ramp (E2), which is 1.2 m above the ground. She travels through the air, reaching a maximum height (E3—this is made as an event for practice purposes) with a speed of 4.1 m/s at a height of 1.7 m. She lands on the top of the next ramp (E4), which has a height of 1.0 m. She then rolls down that ramp, speeding up with an acceleration of 6.5 m/s² till the end of the ramp, which is 2.5 m long (E5).

I need help with this one question: what is the velocity at event 2
Relevant Equations
the big 5 equation, uniform motion and projectile motion
I have tried to use the projectile motion to find Vx and Vy, however since the angle isn't given, I don't think this problem can be solved with only motion formulas (I did solve it with energy formulas).
 
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Welcome to PF. The problem statement is confusing to me, especially this part:
She travels through the air, reaching a maximum height (E3—this is made as an event for practice purposes) with a speed of 4.1 m/s at a height of 1.7 m.
Is there a diagram that goes with this problem? You can upload it using the "Attach files" link below the Edit window. And if that is her "speed" at her maximum height, which direction is she traveling at that point?

Also, for your Relevant Equations, are there any Energy equations that you think might be pretty handy? :wink:
 
StrugglingStudent123 said:
Homework Statement: A skateboarder starts at the bottom of a ramp (E1) with a speed of 7.2 m/s. She rolls up the ramp, slowing down with an acceleration of -6.1 m/s², and finally leaves the end of the ramp (E2), which is 1.2 m above the ground. She travels through the air, reaching a maximum height (E3—this is made as an event for practice purposes) with a speed of 4.1 m/s at a height of 1.7 m. She lands on the top of the next ramp (E4), which has a height of 1.0 m. She then rolls down that ramp, speeding up with an acceleration of 6.5 m/s² till the end of the ramp, which is 2.5 m long (E5).

I need help with this one question: what is the velocity at event 2
Relevant Equations: the big 5 equation, uniform motion and projectile motion

I have tried to use the projectile motion to find Vx and Vy, however since the angle isn't given, I don't think this problem can be solved with only motion formulas (I did solve it with energy formulas).
It is unclear whether mechanical energy is conserved up to E2. If it is, the state at E3 is overspecified. (Indeed, based on the other information the height should be 1.78m.)
I suggest working backwards from the E3 information.
 
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