If the echo (the reflected sound) reaches your ear less than about
0.1 second after the original sound, your brain doesn't separate them,
and you're not aware of the echo even though it's there.
If the echo comes from, say, a wall, 0.1 second means you'd have to be
about 17 meters away from the wall. If you're closer than that, then the
echo reaches you in less than 0.1 second and you're not aware of it.
A. 30 meters . . .
No. You hear that echo easily
B. you're standing within range of both sounds . . .
No. You hear that echo easily, if you're at least 17 meters from the wall.
C. less than 0.1 second later . . .
That's it. The echo is there but your brain doesn't know it.
D. 21.5 meters
No. You hear that echo easily.
Answer:
The light bends away from the normal
Explanation:
We can solve the problem by using Snell's law:
where:
is the index of refraction of the first medium
is the index of refraction of the second medium
is the angle of incidence (angle between the incoming ray and the normal to the interface)
is the angle of refraction (angle between the outcoming ray and the normal to the interface)
We can rearrange the equation as
In this problem, light travels from an optically denser medium to an optically rarer medium, so
Therefore, the term 
is greater than 1, so
which means that the angle of refraction is greater than the angle of incidence, and so the light will bend away from the normal.
Answer:
cell
Explanation:
here are all the symbols-
hope this helps, take care and stay safe
Answer:
Explanation:
Given
Wheels are rotating with constant angular velocity let say 
Presence of constant angular velocity show that there is no angular acceleration thus there is no tangential acceleration.
But any particle on the rim will experience a constant acceleration towards center called centripetal acceleration.
(a) yes, there will be tangential velocity which is given by
where r=radial distance from center
(b)tangential acceleration
there would be no tangential acceleration as velocity is constant
(c)centripetal acceleration
Yes, there will be centripetal acceleration given by
Let volume of empty boat be = 100% = 1V
and mass of boat be M
In water 10%, 0.1V of the volume is submerged.
Mass, m of 1200kg increases the submerging from 10%, 0.1V to 70%, 0.7V
M leads to 0.1V boat submerging
boat submerging.
M + 1200kg leads to 0.7V boat submerging.
This is 60%, 0.6 V increase
By comparison
(M+1200kg) * 0.1V = 0.7V * M
0.1M + 120kg = 0.7M
120kg = 0.7M - 0.1M
120kg = 0.6M
M = (120/0.6)kg
M = 200kg.
The mass of the boat is 200kg.
