Apropeller consists of two blades each 3.0 m in length and mass 120 kg each. the propeller can be approximated by a single rod rotating about its center of mass. the propeller starts from rest and rotates up to 1200 rpm in 30 seconds at a constant rate.

a) what is the angular momentum of the propeller at =10s; =20s?
b) what is the torque on the propeller?

Explanation:

a)

= length of each blade = 3 m

= mass of each blade = 120 kg

= length of the rod

= mass of the rod

Length of the rod is given as

= Angular velocity at t = 0, = 0 rad/s

= Angular velocity at t = 30, = 1200 rpm = 125.66  rad/s

= time interval = 30 - 0 = 30 s

angular acceleration is given as

Angular velocity at t = 10 s is given as

Angular velocity at t = 20 s is given as

Mass of the rod is given as

Moment of inertia of the propeller is given as

Angular momentum at t = 10 s is given as

Angular momentum at t = 20 s is given as

b)

Torque on propeller is given as

the components of a vector are the parts of the vectors that are to each other.

b perpendicular