Question

A rotating body with moment of inertia 6 × 10–4 kg m2 has a kinetic energy 12 J. The angular momentum of the body is
0.12 kg m2/s
61 kg m2/s
12 × 107 kg m2/s
0.61 kg m2/s

Answer 1

Given:

Moment of Inertia of the rotating body = 6*10⁻⁴ kg m²

Kinetic energy = 12 J

To find:

Angular momentum of the body.

Solution:

The angular momentum of the body = Iω

While kinetic energy = 1/2*Iω² = 12 J

Therefore, on putting the values we get:

1/2* 6*10⁻4 *ω² = 12

Taking ω² on the LHS:

ω² = 4*10⁴ rad/s

Taking root both the sides, we get:

ω = 2*10² = 200 rad/s

The angular momentum of the body =  Iω = 6*10⁻⁴*200 = 12*10⁻² = 0.12 kg m² /s

The angular momentum is 0.12 kg m²/s. Option A is correct.

Answer 2

HELLO DEAR,

GIVEN :-

Moment of inertia (l) of a body = 6 × 10^-4 kg m².

Kinetic energy of the rotating body (K)= 12 J.

To find angular momentum (L) of the body.

SOLUTION:-

we know that,

I = L / ω

∵. L = lω

And kinetic energy of rotation body, K = lω²/2

And K = 12 J (given)

So, lω²/2 = 12

=> Iω² = 24

=> 6 × 10^-4 × ω² = 24

=> 10^-4 × ω² = 4

=> ω² = 40000

=> ω = 200 rad/s.

So,

angular momentum of a body (L) = lω

∴ L = lω

L = 6 × 10^-4 × 200

L = 0.12 kg m2/s.

Therefore option (A) 0.12 kg m2/s

I HOPE IT'S HELP YOU DEAR,

THANKS.