katamoria
Oct31-09, 01:28 PM
1. The problem statement, all variables and given/known data
a. compute the torque developed by an industrial motor whose output is 225kW at an angular speed of 4000rpm.
b. a drum with negligible mass and .4m diameter is attached to the motor shaft, and the power output of the motor is used to raise a weight hanging from a rope wrapped around the drum. how heavy a weight can the motor life at constant speed?
c. at what constant speed will the weight rise?
2. Relevant equations
rpm x 2pi/60s = rad/s angular speed (w) = 418 rad/s
1Kw = 3.6x10^6J
Power = (torque)(angular speed)?
V = Rw
3. The attempt at a solution
i changed the w from rpm to rad/s
I converted kW to J and got 81x10^8J
I'm not sure that's right, that seems really big to me.
and if Power = (torque)(angular velocity) then i rearranged and solved for torque and got 19.4x10^6, which seems high to me
I have no idea what to do with part B
I know that tension in the rope equals the weight of the object tied to it.
a. compute the torque developed by an industrial motor whose output is 225kW at an angular speed of 4000rpm.
b. a drum with negligible mass and .4m diameter is attached to the motor shaft, and the power output of the motor is used to raise a weight hanging from a rope wrapped around the drum. how heavy a weight can the motor life at constant speed?
c. at what constant speed will the weight rise?
2. Relevant equations
rpm x 2pi/60s = rad/s angular speed (w) = 418 rad/s
1Kw = 3.6x10^6J
Power = (torque)(angular speed)?
V = Rw
3. The attempt at a solution
i changed the w from rpm to rad/s
I converted kW to J and got 81x10^8J
I'm not sure that's right, that seems really big to me.
and if Power = (torque)(angular velocity) then i rearranged and solved for torque and got 19.4x10^6, which seems high to me
I have no idea what to do with part B
I know that tension in the rope equals the weight of the object tied to it.