Tips on solving 2D Kinematic problems

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    2d Kinematic Tips
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Discussion Overview

The discussion focuses on strategies for solving 2D kinematics problems, emphasizing the independence of dimensions and the necessary quantities for problem-solving. Participants share tips and approaches to enhance understanding and problem-solving skills in this area of physics.

Discussion Character

  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant suggests writing down given quantities and what is being asked before solving, using symbols until the end.
  • Another participant emphasizes that 2D kinematics problems can be treated as two independent 1D problems, with time being the only common factor.
  • A further contribution states that to solve for motion in each direction, three of the five quantities (displacement, initial velocity, final velocity, acceleration, and time) must be known.
  • For projectile motion, one participant notes that the x-direction has constant velocity and provides the equation Δx = vx·t, while the y-direction involves constant acceleration due to gravity.
  • It is mentioned that solving a projectile problem typically requires knowing two quantities from the x-direction equation and three from the y-direction quantities.

Areas of Agreement / Disagreement

Participants generally agree on the independence of dimensions in 2D kinematics and the necessity of specific quantities for solving problems. However, there are no explicit disagreements noted in the contributions.

Contextual Notes

Some assumptions about the conditions of motion, such as neglecting air resistance in projectile motion, are not explicitly stated. The discussion does not resolve potential variations in approaches to different types of 2D kinematics problems.

Who May Find This Useful

This discussion may be useful for students struggling with 2D kinematics concepts, educators seeking alternative explanations, or anyone interested in enhancing their problem-solving strategies in physics.

Goopy17
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Hi,
This isn't a homework question. I need help on how to go about solving 2D kinematics problems. My teacher is terrible and doesn't even teach. It seems like it should be pretty straight forward with solving these, but I'm just having a hard time. If someone could give me tips on how to go about solving, it would make my life so much easier.
Thanks!
 
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Write down the given quantities at the top of the page. Write down what you are asked to do, You should read the question at least twice to be sure of what is asked of you. Begin solving the problem using symbols to represent quantities. Do not plug in numbers until the end.
 
The most important thing to remember in 2D kinematics problems is that the two dimensions are entirely independent of each other. So that means you are never actually doing a 2D kinematics problem, you are always doing two 1D kinematics problems at the same time. Literally-- t is the same in the two problems, that's all that connects them.
 
I agree with Ken G. Furthermore, for each direction (x or y), you need to know 3 of the 5 quantities (displacement, initial velocity, final velocity, acceleration, and time) in order to solve for the motion.

For projectile problems, there is a constant velocity in the x-direction. So there is really just one equation describing the x motion:
Δx = vx·t​
In the y-direction, there is a constant acceleration of g acting downward. The kinematic equations you learned earlier in the course all apply here.

To completely solve a projectile problem you generally need to know:
(1) Two of the three quantities in the Δx = vx·t equation, and
(2) Three of the 5 quantities involved in the y-direction: Δy, vy,initial, vy,final, ay, and t. And you already know ay.
 
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