<span>Dark Energy causes the Universe to accelerate outward. Dark Matter is the stuff that keeps the Universe together. </span>
        
             
        
        
        
Answer:
Time period between the successive beats will be 0.1703 sec 
Explanation:
We have given speed of the sound v = 349 m/sec
Wavelength of piano 
Wavelength of piano  
So frequency of piano A 
Frequency of piano B 
So beat frequency f = 455.61 - 449.74 = 5.87 Hz
So time period 
So time period between the successive beats will be 0.1703 sec 
 
        
             
        
        
        
Phenyl oxalate ester is responsible for the luminescence in aglow stick<span>. The reaction with hydrogen peroxide </span>causes<span> the liquid inside a </span><span>glow stick to glow</span>
        
             
        
        
        
Speed = distance / time.
Speed of him leaving the nest:
S = 100 / 20sec
5 m/s.
Catching the snake:
S2 = 50 / 5sec
10 m/s.
Average of 5& 10 = 7.5 
7.5 m/s has to be the answer.