I with rotational kinetic energy problems

Click For Summary
SUMMARY

The discussion centers on calculating rotational kinetic energy using the formula KE = (1/2)(I)(ω)^2. The user initially calculated the kinetic energy for a rotating object with a mass of 2000 kg and a radius of 0.125 m, converting 3600 RPM to 376.8 rad/s, resulting in an answer of 1.1 x 10^6 J, while expecting 2218410 J. For a second scenario involving a 7 kg object, the user calculated 21 J using the same formula but expressed uncertainty about the accuracy of their results. The user also inquired about the moment of inertia (MoI) for a solid uniform sphere.

PREREQUISITES
  • Understanding of rotational kinetic energy and its formula KE = (1/2)(I)(ω)^2
  • Knowledge of converting RPM to rad/s
  • Familiarity with moment of inertia (MoI) calculations
  • Basic principles of physics related to work and energy
NEXT STEPS
  • Research the moment of inertia formula for a solid uniform sphere: I = (2/5)mr^2
  • Learn how to convert RPM to rad/s accurately
  • Study the relationship between work and change in kinetic energy
  • Explore examples of rotational kinetic energy problems for practice
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and rotational dynamics, as well as educators seeking to clarify concepts related to kinetic energy and moment of inertia.

kenny243
Messages
2
Reaction score
0
B9aoQgo.png
I tried to use this formula: KE=(1/2)(I)(w)^2, and work=change in KEFor the first question, i tried to plug the number into the rotation kinetic energy formula:
3600rpm=376.8rad/s
(0.5)(2,000kg)(0.125m)^2(376.8rad/s)^2
I found out this was the answer 1.1 x 106 J, but I got 2218410J

For the second one, I did:
(0.5)(7kg)(0.109)^2((6m/s)/(0.1m))^2
And I got 21j, pretty sure is wrong.

Can someone please help me out, or give me a hint??
Really struggling.
Does the change in kinetic energy equal to work?
 
Last edited by a moderator:
Physics news on Phys.org
kenny243 said:
I got 2218410J
I get about the same.
kenny243 said:
For the second one, I did:
(0.5)(7kg)(0.109)^2((6m/s)/(0.1m))^2
What's the formula for the MoI of a solid uniform sphere?
 

Similar threads

  • · Replies 21 ·
Replies
21
Views
5K
  • · Replies 33 ·
2
Replies
33
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
Replies
9
Views
3K
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 3 ·
Replies
3
Views
4K