Angular acceleration and angular velocity

  • Thread starter John78
  • Start date
  • #1
21
0

Homework Statement



Calculate the angular acceleration and angular velocity of a 4 kg object rotating in a circle of 3 m radius in a time of 6 s.

Homework Equations





The Attempt at a Solution



Angular acceleration = ω2*r

C=2∏r= 2*3.14*3=18.84
360°/57.3°=6.28 rad/s
6.28/6= 2.09 rad/sec

Angular acceleration= (2.09)2*3=12.54???????


Angular velocity= angular displacement/time ????



I just want to check whether my working is correct or not.
 

Answers and Replies

  • #2
296
0
Nope.Its not right.

Remember, angular acceleration is dw/dt.

The acceleration w^2*r is centripetal accelwration.

Infact writing angular acceleration as w^2*r is dimemsionally inconsistent.


As nothing had been told about how w changes with time nothing can be said about angular acceleration.

In such cases w is assumed to be constant making angular acceleration 0
 
  • #3
21
0
angular acceleration = 0


what about angular velocity?
 
  • #4
tiny-tim
Science Advisor
Homework Helper
25,832
251
Hi John78! :smile:
angular acceleration = 0
Correct.
what about angular velocity?
Your formula …
Angular velocity= angular displacement/time
… is fine :smile:
 

Related Threads on Angular acceleration and angular velocity

Replies
5
Views
8K
Replies
3
Views
4K
Replies
4
Views
30K
Replies
3
Views
2K
Replies
10
Views
5K
Replies
2
Views
1K
Replies
26
Views
69K
  • Last Post
Replies
11
Views
3K
  • Last Post
Replies
1
Views
6K
  • Last Post
Replies
1
Views
302
Top