Solving projectile motion equations

Click For Summary

Discussion Overview

The discussion revolves around understanding the equations of projectile motion, specifically addressing the interpretation of units and the mathematical treatment of variables within the equations.

Discussion Character

  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about the presence of both "s^2" and "delta t" in an equation, questioning how they can cancel out when both appear to be unknowns.
  • Another participant clarifies that "s" is not an unknown but a unit for seconds, suggesting a misunderstanding of the notation.
  • A participant questions the necessity of squaring the unit of time, seeking clarification on why it appears in second degree.
  • Further clarification is provided regarding the treatment of units, explaining that units can be squared and undergo operations similar to variables, using acceleration as an example.
  • Another participant offers alternative representations of the unit to avoid confusion, such as writing it as m/ss or (m/s)/s.
  • A later reply indicates that the discussion has led to a deeper understanding of the logic behind the equations.

Areas of Agreement / Disagreement

Participants appear to have differing levels of understanding regarding the treatment of units in equations, with some clarifications offered but no consensus reached on the initial confusion about the equation.

Contextual Notes

The discussion highlights potential limitations in understanding the notation and operations involving units, particularly in the context of physics equations.

Femme_physics
Gold Member
Messages
2,548
Reaction score
1
Solving projectile motion equations...

Trying to understand this equation...

http://img541.imageshack.us/img541/2658/carqk.jpg

Uploaded with ImageShack.us

When you get to the end of this equation, there's s^2 and delta t..

That seems like two unknowns to me. How do they both cancel out?
 
Last edited by a moderator:
Physics news on Phys.org


Er... "s" is not an unknown. It is a unit for "seconds".

Zz.
 


Okay, but why is it in second degree? Why did they need to add ^2 into a unit?
 


Femme_physics said:
Okay, but why is it in second degree? Why did they need to add ^2 into a unit?

Er.. it seems that you appear to not know that units can be squared, or undergo the same operations as a variable.

An acceleration, for example, is [itex]L/T^2[/itex], where L is length, T is time. So since the time dimension is squared, the units is also squared. In SI units, it is [itex]m/s^2[/itex]. If you don't like the square symbol, then write it as [itex]m/ss[/itex]. There, no more squared.

Zz.
 


ZapperZ said:
If you don't like the square symbol, then write it as [itex]m/ss[/itex].

Or as (m/s)/s: (meters per second) per second.
 


Ah...a little deeper ponderage after your replies got me to see the logic :) mercy.
 

Similar threads

Undergrad How to Solve Projectile Motion Problems in One or Two Lines
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Projectile Intercept Math & Trigonometry
  • · Replies 4 ·
Replies
4
Views
2K
High School Maximum velocity for projectile motion?
  • · Replies 25 ·
Replies
25
Views
5K
Undergrad Projectile Motion: Path's length?
  • · Replies 18 ·
Replies
18
Views
3K
Graduate Path of a projectile with a non-constant gravity
  • · Replies 5 ·
Replies
5
Views
2K
High School Key equation with uniform acceleration and projectile motion
  • · Replies 5 ·
Replies
5
Views
2K
Undergrad Gun-projectile Elastic Collisions
  • · Replies 13 ·
Replies
13
Views
2K
High School Question regarding projectile motion
  • · Replies 11 ·
Replies
11
Views
2K
Graduate Angle required to hit the target in projectile motion
  • · Replies 2 ·
Replies
2
Views
4K
Undergrad Is my equation for projectile trajectory accurate?
  • · Replies 7 ·
Replies
7
Views
3K