- #1
valvan1
- 3
- 0
so a student is sitting on a spinning stool and has a 2kg dumbbell in each hand angular velocity is 3rad/sec arms stretched out is a radius of 80cm and he pulls in his arms to 20cm. for this problem your ignoring the students weight.
from other problems i have figured out
so angular velocity to start with is 3 rad/sec
angular velocity final is 48 rad/sec
kinetic energy initial is 11.52( don't know what dimensions this is I am guessing J)
kinetic energy final is 184.32
and i need to find the force required to pull on of the dumbells in at a constant speed is equal to F=((initial angular momentum of 1 block)^2)/(4*Mass of one weight*Radius^3)) or do i use the change in kinetic energy equation ?
do i say Torque=F*d and Torque=I*alpha and then go Force = Ia/d? or is there another way to solve this that I am not seeing ?
from other problems i have figured out
so angular velocity to start with is 3 rad/sec
angular velocity final is 48 rad/sec
kinetic energy initial is 11.52( don't know what dimensions this is I am guessing J)
kinetic energy final is 184.32
and i need to find the force required to pull on of the dumbells in at a constant speed is equal to F=((initial angular momentum of 1 block)^2)/(4*Mass of one weight*Radius^3)) or do i use the change in kinetic energy equation ?
do i say Torque=F*d and Torque=I*alpha and then go Force = Ia/d? or is there another way to solve this that I am not seeing ?