A barbell has two 20 kg masses on the ends of a 10-kg rod that is 1.3 m long. The rod rotates about its mid-point at 11 rpm. What is the magnitude of the barbell's angular momentum

The magnitude of the barbell's angular momentum is 38.947 kg /s

Explanation:

Given the mass of the barbell = 20 kg

mass of the rod = 10 kg

Length of the rod L = 1.3 m

rotation speed of the rod = 11 rpm

                   = 11 rpm x 2π/1 rev x 1 min/ 60 sec = 1.152 rad/sec

Angular momentum (L) = Iω............................1

I is the moment of inertia and ω is the angular sped.

As shown in the equation angular momentum is a product of angular speed and moment of inertia, the moment of inertia can be calculated thus;

I  =

I =[ x 10 x] + 2[20 x(0.5 x 1.3]

I =  1.408 + 32.4

I = 33.808 kg

Therefore, the moment of inertia is 33.808 and inputting the value in equation 1 we have;

L = 33.808  x 1.152

L = 38.947 kg /s

Therefore, the angular momentum of the barbell is 38.947 kg /s

the bal will not change its velocity.

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