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
Answer:
-20°C
Explanation:
The specific heat capacity of ice using the cgs system is 0.5cal/g°C
The enthalpy change is calculated as follows
ΔH=MC∅ where M represents mass C represents specific heat and ∅ represents the temperature change.
10cal = 2g×0.5cal/g°C×∅
∅=10cal/(2g×0.5cal/g°C)
∅=10°C
Final temperature= -30°C+ 10°C= -20°C
Option C would be the right one
Answer:

Explanation:
Height of man= 6ft
Height of light=1 5ft
Let BC=x and CD=y
BD=x+y
Triangle ABD and ECD are similar
When two triangles are similar then the ratio of their corresponding sides are equal






Differentiate w.r.t t

We have 
Substitute the value then we get


Rate at which the tip of shadow is moving=
Rate at which the tip of shadow is moving=
Rate at which the tip of shadow is moving=
Answer:
1. Battery
2. Copper wire
3. Nail or piece of metal (zinc, iron, or steel).