Answer:
A) The wave that travels through the rail reaches the microphone first.
B) separation in time between the arrivals of the two pulses is 0.01539 seconds.
Explanation:
Detailed explanation and calculation is shown in the image below
Answer:

we can see that this time period is independent of the mass of the child so answer would be same if the child mass is different
Explanation:
Natural frequency of a simple pendulum of L length is given as

so the time period of the oscillation is given as

so we will have



also from above formula we can see that this time period is independent of the mass of the child so answer would be same if the child mass is different
Answer: 
Explanation:
Given
Mass of water is 
mass of ice is 
Latent heat of fusion 
The heat capacity of water is 
Suppose water is at
and it reaches to
to melt the ice
the heat released by water must be equivalent to heat absorbed by the ice

Answer:
θ = 66.90°
Explanation:
we know that

I= intensity of polarized light =1
I_o= intensity of unpolarized light = 13
putting vales we get

⇒
therefore θ = 66.90°
Answer:

Explanation:
Thinking process:
Let:
distance = speed × time
for the hare:

for the tortoise:

Let the length of the shell be s. Then the two are related. So:

Let's say the hare ran at x times the speed of the tortoise:

So, the equation still holds :