Solving Torque Unit Issue: kg*m3/s2 ≠ kg*m2/s2

  • Thread starter Thread starter Chad Jensen
  • Start date Start date
  • Tags Tags
    Torque
Click For Summary
SUMMARY

The discussion centers on the confusion surrounding torque units, specifically the relationship between torque (T), moment of inertia (I), and angular acceleration (α). The correct formula is τ = Iα, where τ represents torque in N*m, I is in kg*m², and α is in rad/s². The participant initially misinterpreted the units, equating kg*m³/s² with kg*m²/s², which is incorrect. The clarification emphasizes that radians are dimensionless, simplifying the unit analysis.

PREREQUISITES
  • Understanding of torque and its units (N*m)
  • Familiarity with moment of inertia (kg*m²)
  • Knowledge of angular acceleration (rad/s²)
  • Basic grasp of dimensional analysis in physics
NEXT STEPS
  • Study the relationship between torque and angular acceleration using τ = Iα
  • Explore dimensional analysis techniques in physics
  • Learn about the significance of radians in angular measurements
  • Investigate common mistakes in unit conversions in mechanics
USEFUL FOR

Students in physics, educators teaching mechanics, and anyone seeking clarity on torque and rotational dynamics.

Chad Jensen
Messages
11
Reaction score
1

Homework Statement


Not really a homework question but a question about units that I can't figure out.

Homework Equations


Torque units = N*m
N=kg*m/s2
I units = kg*m2
a units = m/s2
Now my formula sheet says T=Ia

The Attempt at a Solution



torque=kg*m/s2*m=kg*m2/s2
Ia=kg*m2/s2*m/s2=kg*m3/s2
kg*m3/s2 in not equal to kg*m2/s2 What am I doing wrong?
Thanks for any help
 
Physics news on Phys.org
Chad Jensen said:
Now my formula sheet says T=Ia
It should say ##\tau = I \alpha## where ##\alpha## is the angular acceleration.
 
  • Like
Likes   Reactions: Chad Jensen
Oh ok. That makes more sense. Thank you so, it is rad/s^2 which rads are considered dimensionless so they can be eliminated with no need to cross multiply or subtract to make them go away. You are then left with 1/s^2. Thank you I knew I was missing something simple. I looked at the formula sheet and it was alpha and not a
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 18 ·
Replies
18
Views
7K
  • · Replies 11 ·
Replies
11
Views
4K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 8 ·
Replies
8
Views
9K