**Answer**

given,

vertical speed of stone,v = 12 m/s

height of the cliff = 70 m

a) time taken by the stone to reach at the bottom of the cliff

We know that,

S = u t + 1/2 a t²

- 70 = 12 t - 0.5 x 9.8 t²

4.9 t² - 12 t - 70 = 0

solving the equation

**t = 5.2 s** (neglecting the negative value)

b) again using equation of motion

v = u + a t

v = 12 - 9.8 x 5.2

v = -38.96 m/s

ignoring the negative sign

magnitude of velocity is equal to** 38.96 m/s**

c) total distance travel by the stone

vertical distance covered by the stone

v² = u² + 2 g h

0 = 12² - 2 x 9.8 x h

** h = 7.34 m**

to reach the stone to the same level distance travel be doubled.

Total distance travel by the stone

H = h + h + 70

H = 7.34 x 2 + 70

** H = 84.7 m.**

She hung up the pieces of cotton BEFORE putting the fan on, also the water evaporating can take longer or shorter even if they are all the same :))

January 1st 2000

Hope this helps:):):):):)

<span>We can think this through intuitively. A frequency of 256 Hz means that the wave has 256 cycles each second. If the wavelength is 1.33 meters, then there are 256 of them each second. Therefore, we just need to multiply the wavelength by the frequency to find the speed of sound. (Note that the units Hz = 1 / s)
v = (frequency) x (wavelength)
v = (256 Hz) x (1.33 m)
v = 340.5 m/s
The speed of sound in the vicinity of the fork is 340.5 m/s</span>

**Answer:**

**Explanation:**

Since the collision is perfectly elastic collision so here we can use momentum conservation

so we will have

also by elastic collision property we will have

now from above two equations we have