If a ball is thrown upward with velocity of 1m/s, is vx = 0 while vy= 1?

  • Context: High School 
  • Thread starter Thread starter cmkc109
  • Start date Start date
  • Tags Tags
    Ball Velocity
Click For Summary

Discussion Overview

The discussion centers on the behavior of a ball thrown vertically with an initial velocity of 1 m/s, specifically examining the components of velocity (vx and vy) and acceleration (ax and ay) based on different choices of coordinate axes. The scope includes conceptual understanding and the implications of axis selection in physics problems.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that if the ball is thrown straight upwards, then vx = 0 and vy = 1 m/s, assuming the y-axis points straight up.
  • Others propose that if the x-axis is chosen to point straight up, then ay = 0 and ax = -9.8 m/s², which was confirmed by another participant.
  • One participant discusses the flexibility of axis choice, suggesting that different orientations (e.g., both axes at 45 degrees) can yield valid results, although it complicates calculations.
  • Another participant reflects on the importance of consistency in axis choice throughout a problem, noting that different conventions can simplify or complicate the analysis.

Areas of Agreement / Disagreement

Participants generally agree on the validity of different axis choices but express differing views on the implications and ease of calculations based on those choices. The discussion remains unresolved regarding the best approach to take in various scenarios.

Contextual Notes

Limitations include the dependence on the chosen coordinate system and the potential for confusion when switching conventions mid-problem. The discussion does not resolve the optimal choice of axes for all situations.

cmkc109
Messages
103
Reaction score
0
If a ball is thrown upward with velocity of 1m/s, is vx = 0 while vy= 1?
 
Physics news on Phys.org
cmkc109 said:
If a ball is thrown upward with velocity of 1m/s, is vx = 0 while vy= 1?

Yes, assuming that the ball is thrown straight upwards and the y-axis has been chosen to point straight up.

And now that you have the easy yes/no answer that you were looking for...

You could have chosen the x-axis to point straight up, in which case vx would be 1 and vy would be zero.

Or you could have chosen both axes sloping in opposite directions at a 45-degree angle to the ground. In this case both vx and vy would be equal to √2/2 and there's nothing wrong with that choice except that it complicates the math for no good reason.
 
if i choose x-axis to point straight up, does that mean ay= 0 and ax= -9.8m/s^2?
 
cmkc109 said:
if i choose x-axis to point straight up, does that mean ay= 0 and ax= -9.8m/s^2?

Yes.
 
ok thx!
 
cmkc109 said:
if i choose x-axis to point straight up, does that mean ay= 0 and ax= -9.8m/s^2?

This is a 'confidence thing" I think. When you're a student and the teacher draws axes on the blackboard, everyone thinks "Why ever did she choose that set of axes?". The answer is pretty much always that they have found that they get the right answer to that problem quicker and easier that way.
There's a great example where you are dealing with objects on an inclined plane - do you use vertical and horizontal axes or do you use parallel and normal to the plane? It doesn't really matter but one way will turn out easier for some problems and the other will turn out better for others.
The only thing you need to remember is to keep rigidly with whatever convention you started with for the whole duration of your answer. The up/down thing can give you grief, too.
 

Similar threads

High School What Happens to a Ball's Energy When Thrown Upwards?
  • · Replies 13 ·
Replies
13
Views
3K
High School Path traced by a point on the periphery of the ball? Helix?
  • · Replies 6 ·
Replies
6
Views
1K
Projectile Motion Problem Involving Initial Velocity and Gravity Only
  • · Replies 11 ·
Replies
11
Views
2K
High School Can energy be decomposed?
  • · Replies 2 ·
Replies
2
Views
2K
High School The physics of flywheel launchers (like tennis ball shooters)
  • · Replies 60 ·
3
Replies
60
Views
8K
Undergrad Relative velocities of balls on reaching the ground.
  • · Replies 12 ·
Replies
12
Views
2K
High School Misleading Textbook Equation for vf^2=vi^2 + 2ad
  • · Replies 3 ·
Replies
3
Views
4K
Undergrad Velocity graph, a ball is thrown upward
  • · Replies 14 ·
Replies
14
Views
40K
Undergrad Solve Velocity Equation: -g(horizontal distance)/sin(2theta)
  • · Replies 1 ·
Replies
1
Views
2K
High School Using "symmetry" to deduce final velocities of two colliding particles
  • · Replies 8 ·
Replies
8
Views
1K