A gate to a bullpen is open at a right angle to the fence and the bull is rushing toward the opening to get out. The farmer estimates that the bull will reach the opening in 3 sec. so he pushes at the end of the gate (always at a right angle) with a force of 100N. The moment of inertia of the gate about the hinge is 1,000 kg m^2 and the gate length is 3.
a. What is the magnitude of the torque applied by the farmer.
b. What is the rotational kinetic energy of the gate after 3 seconds
c. Through what angle will the gate have rotated after 3 sec.
d. Will the gate be closed.
Torque, KE roational, Angular Kinematics
The Attempt at a Solution
a. Torque= rFsin(theata) = (3)(100)sin90= 300Nm
b. KE= (1/2)(I)(w^2) = (1/2)(1000)(?)
c. angle= at^2/2?