Question

A propeller is modeled as five identical uniform rods extending radially from its axis. The length and mass of each rod are 0.715 m0.715 m and 2.51 kg2.51 kg , respectively. When the propellor rotates at 527 rpm527 rpm (revolutions per minute), what is its rotational kinetic energy?

Answer 1

3260.33 J

Step-by-step explanation:

`n` = number of rods = 5

`L` = length of each rod = 0.715 m

`m` = mass of rod = 2.51 kg

`I` = total moment of inertia

Total moment of inertia is given as

`I = (nmL^(2))/(3)`

`I = ((5)(2.51)(0.715)^(2))/(3)`

`I` = 2.14 kgm²

`w` = angular speed = 527 rpm = 55.2 rad/s

Rotational kinetic energy is given as

E = (0.5)
`I` (
`w` )²

E = (0.5) (2.14) (55.2)²

E = 3260.33 J