Answer:
57.6Joules
Explanation:
Rotational kinetic energy of a body can be determined using the expression
Rotational kinetic energy = 1/2Iω²where;
I is the moment of inertia around axis of rotation. = 5kgm/s²
ω is the angular velocity = ?
Note that torque (T) = I¶ where;
¶ is the angular acceleration.
I is the moment of inertia
¶ = T/I
¶ = 3.0/5.0
¶ = 0.6rad/s²
Angular acceleration (¶) = ∆ω/∆t
∆ω = ¶∆t
ω = 0.6×8
ω = 4.8rad/s
Therefore, rotational kinetic energy = 1/2×5×4.8²
= 5×4.8×2.4
= 57.6Joules
Answer:
20 rad/s
Explanation:
mass, m = 12 kg
radius, r = 0.250 m
Moment of inertia of cylinder, I = 1/2 mr²
I = 0.5 x 12 x 0.250 x 0.250 = 0.375 kgm^2
Work done = Change in kinetic energy
Initial K = 0
Final K = 1/2 Iω²
W = 1/2 Iω²
ω² = 2W/ I = 2 x 75 / (0.375)
ω = 20 rad/s
Thus, the final angular velocity is 20 rad/s .