Why are work and energy different even though they have the same units?

Click For Summary

Discussion Overview

The discussion revolves around the relationship between work and energy, specifically why both are measured in Joules yet are considered different concepts. Participants explore definitions, units, and the conceptual distinctions between work and energy in the context of physics.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that both work and energy are measured in Joules, leading to questions about their definitions and differences.
  • One participant suggests that energy can be seen as the ability to do work, prompting further inquiry into the definitions being referenced.
  • Another participant clarifies that the Joule is defined as Newton times meter (N x m), correcting earlier statements about its definition.
  • Some argue that work and energy are two sides of the same coin, as performing work on an object results in a change in its energy.
  • Participants discuss that work expresses energy transmission or transformation, which may contribute to their shared unit of measurement.
  • There are assertions that various forms of energy (potential, kinetic) and forces (electrostatic, gravitational) share the same dimensions and units, indicating a broader conceptual framework.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and conceptual distinctions between work and energy. While some agree on the relationship between the two, there is no consensus on their definitions or the implications of their shared unit of measurement.

Contextual Notes

Participants reference definitions and concepts from high school physics, which may not fully capture the nuances of work and energy in advanced contexts. There are also corrections regarding the units of measurement that indicate a potential misunderstanding among participants.

PrakashPrasad
Messages
22
Reaction score
0
Work unit is said to be Joule and Energy unit is also Joule. Work formulas in F x S ( Force x Displacement) .
We know
1 J = 1 F x `1 s
Now Energy is also measured in Joule(J)
So can we state :
E = 1 F x 1 s as 1 J = 1 F x 1 s
that is
E = W

Then why work and energy are different by definition and meaning
 
Physics news on Phys.org
PrakashPrasad said:
We know
1 J = 1 F x `1 s

A small glitch, 1J = 1N x 1s.

PrakashPrasad said:
Then why work and energy are different by definition and meaning

What do you mean by that? A very "rough" statement back from high school times, is "Energy of a body, is the ability to do work". Now, what are the definitions you refer to?
 
QuantumQuest said:
A small glitch, 1J = 1N x 1s.

I am not sure if you mean to correct a glitch or to present one. :)
The Joule is not Nxs (Newton times second).

The OP meant Force x distance when he/she wrote 1J= 1F x 1s (by s probably meaning distance, displacement).
 
QuantumQuest said:
A small glitch, 1J = 1N x 1s.
What do you mean by that? A very "rough" statement back from high school times, is "Energy of a body, is the ability to do work". Now, what are the definitions you refer to?
Well is W = E ? I am not going by definition but rather its unit of measurement which in this case is Joule (for both Work & Energy)? So why we state that work is said to be done when a is force applied on a body and it displaces while energy is ability or capacity to do work - why are the unit of measurement same for both work / energy - JOULE?
 
PrakashPrasad said:
Well is W = E ? I am not going by definition but rather its unit of measurement which in this case is Joule (for both Work & Energy)? So why we state that work is said to be done when a is force applied on a body and it displaces while energy is ability or capacity to do work - why are the unit of measurement same for both work / energy - JOULE?
Because work and energy is two sides of the same coin. If you lift a boulder (10kg) up 1m, it means that:
  • You have performed an amount of work = m⋅g⋅h = 10⋅9.81⋅1J = 98J
  • The boulder has gained an amount of potential energy = m⋅g⋅h = 10⋅9.81⋅1J = 98J
 
  • Like
Likes   Reactions: billy_joule
nasu said:
The Joule is not Nxs (Newton times second)

Yes, sorry for the typo, I meant N x m - of course, in SI units.

PrakashPrasad said:
Well is W = E ? I am not going by definition but rather its unit of measurement which in this case is Joule (for both Work & Energy)? So why we state that work is said to be done when a is force applied on a body and it displaces while energy is ability or capacity to do work - why are the unit of measurement same for both work / energy - JOULE?

Work expresses energy transmission or transformation of energy, from one form to another. So, they have the same unit of measurement.
As for the energy concept itself, I recommend this great insight by DaleSpam https://www.physicsforums.com/insights/what-is-energy/.
 
Last edited:
  • Like
Likes   Reactions: PrakashPrasad
PrakashPrasad said:
Well is W = E ? I am not going by definition but rather its unit of measurement which in this case is Joule (for both Work & Energy)? So why we state that work is said to be done when a is force applied on a body and it displaces while energy is ability or capacity to do work - why are the unit of measurement same for both work / energy - JOULE?

Work is a form of energy
Potential energy is a form of energy
Kinetic energy is a form of energy

They ALL have the same dimension and SI units.

The similar way as

Electrostatic force is a form of force
Gravitational force is a form of force
Spring force is a form of force
Tension is a form of force
Frictional force is a form of force

They all have have the same dimension and SI units of N.

Zz.
 
  • Like
Likes   Reactions: PrakashPrasad
QuantumQuest said:
Yes, sorry for the typo, I meant N x m - of course, in SI units.
Work expresses energy transmission or transformation of energy, from one form to another. So, they have the same unit of measurement.
As for the energy concept itself, I recommend this great insight by DaleSpam https://www.physicsforums.com/insights/what-is-energy/.
Work expresses energy transmission or transformation of energy - got it thanks
 
ZapperZ said:
Work is a form of energy
Potential energy is a form of energy
Kinetic energy is a form of energy

They ALL have the same dimension and SI units.

The similar way as

Electrostatic force is a form of force
Gravitational force is a form of force
Spring force is a form of force
Tension is a form of force
Frictional force is a form of force

They all have have the same dimension and SI units of N.

Zz.
Thanks for the details
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 138 ·
5
Replies
138
Views
9K
  • · Replies 41 ·
2
Replies
41
Views
4K
  • · Replies 31 ·
2
Replies
31
Views
4K
  • · Replies 4 ·
Replies
4
Views
8K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K