My Math Forum  

Go Back   My Math Forum > Science Forums > Physics

Physics Physics Forum


Thanks Tree2Thanks
  • 1 Post By Benit13
  • 1 Post By v8archie
Reply
 
LinkBack Thread Tools Display Modes
April 30th, 2015, 07:11 AM   #1
Senior Member
 
Mr Davis 97's Avatar
 
Joined: Feb 2014
From: Louisiana

Posts: 156
Thanks: 6

Math Focus: algebra and the calculus
Question Is v in kinetic energy formula speed or velocity?

I know that kinetic energy is a scalar quantity and thus only has a magnitude, so does this mean that v in (1/2)mv^2 is speed and not velocity?
Mr Davis 97 is offline  
 
April 30th, 2015, 07:28 AM   #2
Senior Member
 
Joined: Apr 2014
From: Glasgow

Posts: 1,884
Thanks: 610

Math Focus: Physics, mathematical modelling, numerical and computational solutions
It doesn't matter because the square of the velocity is actually a dot-product.

$\displaystyle KE = \frac{1}{2} m \vec{v}^2 = \frac{1}{2} m \vec{v} \cdot \vec{v} = \frac{1}{2} m \left|v\right|^2$

The vector notation is a little sloppy, but I hope you get the point.
Thanks from Mr Davis 97
Benit13 is offline  
April 30th, 2015, 07:44 AM   #3
Math Team
 
Joined: Dec 2013
From: Colombia

Posts: 6,446
Thanks: 2118

Math Focus: Mainly analysis and algebra
As Benit says, the $v^2$ is $\vec{v}\cdot\vec{v} = \big||v|\big|^2$ which is the magnitude of the velocity squared or the dot product of the velocity with itself. Either way it's a scalar value with no direction.

In practical terms, yes it's the speed. This should make sense, because energy doesn't have a directional component either.
Thanks from Mr Davis 97
v8archie is offline  
Reply

  My Math Forum > Science Forums > Physics

Tags
energy, formula, kinetic, speed, velocity



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Kinetic and potential energy of an object Mr Davis 97 Physics 3 April 20th, 2015 05:39 PM
How was the formula for kinetic energy found, and who found it? Ganesh Ujwal Physics 3 January 5th, 2015 02:58 AM
On The Energy Formula Anamitra Palit Physics 3 October 2nd, 2012 11:58 PM
Find a two-part formula for the velocity v(t) that is valid sivela Calculus 1 January 27th, 2010 03:50 AM
Find velocity, acc, and speed of particle? remeday86 Calculus 2 March 7th, 2009 07:24 PM





Copyright © 2017 My Math Forum. All rights reserved.