Question

Please I'm so hurry

What is it answer this question ?

A disk rotates with rotational kinetic energy is 70J and the angular momentum is 30 kg.m2/s .what is the value moment of inertia the disk?
A) 6.4 kg.m2
C) 40 kg.m2
B) 2.3 kg.m2
D) 0.43 kg.m2​

Answer 1

The value moment of inertia the disk:

I = 6.4 kg·m²

Step-by-step explanation:

Given:

Tk = 70 J

L = 30 kg·m² / s

_____________

I - ?

Rotational kinetic energy:

Tk = I·ω²/2

Angular velocity:

ω = √ (2·T / I)

Angular moment of a rotating body

L = I·ω = I·√ (2·T / I) = √ (2·T·I² / I ) = √ (2·T·I )

Raising to the second degree:

L² = 2·T·I

The value moment of inertia the disk:

I = L² / (2·T)

I = 30² / (2·70) ≈ 6.4 kg·m²

А) 6.4 кг·м²