Question

The axis X and Z in the plane of a disc are
mutually perpendicular and Y-axis is
perpendicular to the plane of the disc. If the
moment of inertia of the body about X and Y
axes is respectively 30 kg m2 and 40 kg mề then
M.I. about Z-axis in kg m² will be :-
(1) 70 (2) 50 (3) 10 (4) Zero​

Answer 1

Answer:

The M.I about Z axis is 70 kg m^2

Explanation:

According to the problem the axis X and Z and are perpendicular.

The moment of inertia of the body along X axis is 30 kg m^2 and along with Y axis it is 40 kg m^2

Let the moment of inertia of the body is mZ along with Z axis

Now we know that,

m(parallel to the plane ) = Σ m( perpendicular and lying in the plane )

=> mZ = mX + mY

Now putting the values,

=> mZ = 30 + 40

=> mZ  = 70

Answer 2

Answer:

mz = mx + my

put the value of x & y

mz = 30 + 40

mz = 70