Answer:
The frequency is
Explanation:
From the question we are told that
The frequency of the tuning fork is 
The beat period is 
Generally the beat frequency is mathematically represented as


The beat frequency is also represented mathematically as

Where
is the frequency of the piano
So
Answer:

Explanation:
The moment of inertia of the system is equal to the each population and the platform inertia so
Inertia disk

Inertia person

Inertia dog

The Inertia of the system is the sum of each mass taking into account that all exert the force of inertia:



Answer:
140m east
Explanation:
If East is positive then lets rephrase the problem into integers
A truck moves +70 m, then moves -120m, and finally moves +90m.
So totally Displacement = +70-120+90= +140m
Since east is positive, the trucks resultant displacement is 140 m east of origin
Im not 100% sure but I beleive the answer is :Because different celestial body's form different shapes and sized of comets and meterors