Answer:
The answer to this is
6600 Hz to 19,800 Hz
Explanation:
The shape of the human ear is analogous to a closed ended pipe hence
we have λ = 4L or wavelength = 4 * length of the child ear
The frequency c/λ where c = speed of sound = 343 m/s
hence the child's audible range is multiples of 343/(4*0.13) =6600Hz
or 13200 Hz or 19,800 Hz
The generally quoted range of human hearing is 20 Hz to 20 kHz
Answer:

Explanation:
Natural length of the string is given as

length of the string while block is hanging on it

extension in length is given as

now we have strain in the string is given as



similarly we will have cross-sectional area of the string is given as

now the stress in the string is given as




Now Young's Modulus is given as



Answer:
Net force = - 1500 N
Explanation:
We calculate the net force acting using Newton's second Law:

True, I'm not the best when it comes to science, but I'm pretty sure it's this
Answer:
14.47 m/s
Explanation:
The momentum must be preserved before and after the collision:
The total momentum before the collision

where
are the masses of the car moving south and north, respectively, before the collision.
is the velocity of the car moving South. We take the velocity to the North as the positive direction
The total momentum after the collision

where V = 5.22m/s is the velocity of both cars after the collision
We can equalize the 2 equations and plug in the numbers:




