What is wrong with my math here? [Kinematics]

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In summary, the conversation is about a student's attempt to compare initial and final kinetic and potential energy of a skateboarder on a ramp. The student's solution was incorrect due to a mistake in calculating the initial horizontal velocity. The conversation ends with the student expressing relief and gratitude for receiving help.
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Kuzon
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Homework Statement


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Open image in new tab to enlarge please :)

Homework Equations


I was trying to compare the initial KE/PE with the final KE/PE in order to find out how far the skateboarder rose but the solution was wrong for some reason?

Keep in mind the skateboarder is traveling along the HORIZONTAL portion of the ramp at 6.5m/s so when he gets to the top of the ramp he will only be traveling at 5.77m/s by my calculations.

The Attempt at a Solution


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  • #2
Somehow, the skateboarder's initial horizontal velocity morphed from 6.5 m/s to 6.8 m/s in your calculations of KE/PE. Bad handwriting, perhaps? :frown:
 
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SteamKing said:
Somehow, the skateboarder's initial horizontal velocity morphed from 6.5 m/s to 6.8 m/s in your calculations of KE/PE. Bad handwriting, perhaps? :frown:
WOW, thanks so much. I was killing myself over this question and probably spent ~3 hours trying to rack my brain around it even though it's basic physics.
 

Related to What is wrong with my math here? [Kinematics]

1. What is kinematics?

Kinematics is a branch of physics that deals with the motion of objects without considering the cause of the motion. It involves studying the position, velocity, and acceleration of objects and how they change over time.

2. How is kinematics different from dynamics?

Kinematics focuses on describing the motion of objects, while dynamics deals with the forces that cause the motion. Kinematics is concerned with the "what" of motion, while dynamics is concerned with the "why" of motion.

3. What is the difference between speed and velocity?

Speed is a measure of how fast an object is moving, while velocity is a measure of how fast an object is moving in a specific direction. Speed is a scalar quantity, while velocity is a vector quantity that includes both magnitude and direction.

4. How can I calculate acceleration?

Acceleration is the rate of change of velocity over time. It can be calculated by dividing the change in velocity by the change in time. The formula for acceleration is a = (vf - vi)/t, where vf is the final velocity, vi is the initial velocity, and t is the time interval.

5. What are the three equations of motion in kinematics?

The three equations of motion in kinematics are:

  • v = u + at (equation for calculating final velocity)
  • s = ut + 1/2at^2 (equation for calculating displacement)
  • v^2 = u^2 + 2as (equation for calculating final velocity using displacement)
where v is final velocity, u is initial velocity, a is acceleration, t is time, and s is displacement.

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