The recycling of glass, plastic, and metal would highly reduce the amount of the waste being sent to the local landfill. The large plastic container, fiberboards, etc, are removed by hand for this. This sorting makes it easy to recycle and reuse the plastic and fiber materials.
To solve this problem it is necessary to apply the concepts related to frequency and vibration of strings. Mathematically the frequency can be expressed as

Then the relation between two different frequencies with same wavelength would be


The beat frequency heard when the two strings are sounded simultaneously is



We have the velocity of the transverse waves in stretched string as


And,

Therefore the relation between the two is,


Finally substituting this value at the frequency beat equation we have


Therefore the beats per second are 11.92Hz
Answer:
The ratio of electric force to the gravitational force is 
Explanation:
It is given that,
Distance between electron and proton, 
Electric force is given by :

Gravitational force is given by :

Where
is mass of electron, 
is mass of proton, 
is charge on electron, 
is charge on proton, 



So, the ratio of electric force to the gravitational force is
. Hence, this is the required solution.
Answer:Transformer
Explanation:All the other devices generate their own electricity apart from power line and Transformer, power line just carries electricity. A transformer can be used to step up or step down voltages from a source.