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

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SUMMARY

Work and energy are both measured in Joules (J), defined as the product of force (N) and displacement (m). While they share the same unit, work is defined as the process of energy transfer through force applied over a distance, whereas energy represents the capacity to perform work. The discussion clarifies that work expresses energy transmission or transformation, reinforcing that both concepts are fundamentally linked yet distinct in definition and application.

PREREQUISITES
  • Understanding of basic physics concepts such as force, work, and energy.
  • Familiarity with SI units, particularly Joules (J) and Newtons (N).
  • Knowledge of potential and kinetic energy definitions.
  • Basic grasp of energy transformation principles.
NEXT STEPS
  • Explore the relationship between work and energy in mechanical systems.
  • Study the principles of energy conservation in physics.
  • Learn about different forms of energy, including potential and kinetic energy.
  • Investigate the concept of energy transmission in various physical processes.
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Students of physics, educators, and anyone interested in understanding the fundamental differences and connections between work and energy in scientific contexts.

PrakashPrasad
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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
 
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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
 
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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/.
 
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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.
 
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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
 

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