A soild iron cylinder has a radius of 0.250-m and a mass of 145-kg. Calculate the kinetic energy of this cylinder when it is rotating about its axis at a rate of 13.5 rev/s?
a. 163 x 10^4 J
b. .0163 x 10^4 J
c. 1.63 x 10^4 J
d. 16.3 x 10^4 J
2006-07-28 05:16:00 · 5 answers · asked by Lou 1 in Science & Mathematics ➔ Physics
do ur hw urself
2006-07-28 05:18:53 · answer #1 · answered by Anubhav~~!! 3 · 1⤊ 0⤋
Just so that the last answer doesn't steer you wrong: yes, the KE of a particle is 1/2mv^2, but for rotation of a bunch of particles around an axis, you have to account for the different speeds due to the different distances from the axis (it takes more to go around a larger circle, right?) This is what moments of inertia are calculated to do. Now hit the books.
2006-07-28 05:42:00 · answer #2 · answered by Benjamin N 4 · 0⤊ 0⤋
Kinetic energy for rotating objects = (0.5)J*W^2 (NOT what the previous answerer said, that is for purely translational motion.
J is called the polar mass moment of inertia and you can find the equation to calculate that from a web search on the terms.
W is the rotational speed in radians per second. One rotation is equal to 2*pi radians. Again, you have to make that conversion.
You should be able to take it from here.
2006-07-28 05:40:58 · answer #3 · answered by Anonymous · 0⤊ 0⤋
KE=(1/2 )m*V^2
Kinetic energy equals one half mass times velocity squared. Use the total mass of the cylinder, then find out its forward, translational velocity. I could tell you its velocity, but I don't want to take away from the fun in learning :-)
2006-07-28 05:36:47 · answer #4 · answered by Anonymous · 0⤊ 0⤋
E=1/2IW^2,here I is the moment of inertia.w is the angular speed. now I for a cylinder is 1/2mr^2. now find the answer yourself.
2006-07-28 05:57:17 · answer #5 · answered by oneindia 1 · 0⤊ 0⤋