Question

A stone is dropped gently vertically downwards from the top of a 500m high tower into the pond of water at the base. When is the splash heard by a person on the top of the tower from the time of dropping the stone.

Answer 1

The height=500m

h=ut+0.5gt²

we initial velocity is zero

500=0.5 * 10 * t²

t=10 seconds

speed of the sound is 340 m/s

so time taken to travel 500m upwards is 500/340=1.47 sec

TIME TAKEN IS 10+1.47=11.47 sec

Hope it helps...

Answer 2

Answer:

Given,

Distance travelled by sound = height of water

• h = 500 m, g = 10 $\sf{ms}^{-2}$

• Speed of sound $\sf{v}_{3}$ = 340 m/s

Time taken by sound :

$= \tt \frac{h}{v_s} = \frac{500}{340} = 1.4...$

To find time taken by stone to reach down $\sf{(t}_{2)}$

• u = 0, g = 10 m second -square, h = 500 m

$= \tt \: h = {ut}^{2} + \frac{1}{2} \: {gt}^{2} _2 \: or \: h \: = \frac{1}{2} {gt}^{2} _2 \\ \\ \tt = t_2 = \sqrt{ \frac{2h}{g} } = \frac{ \sqrt{2 \times 500} }{10} = 10 \: s \\ \\ \bf total \: time \: = \\ \\ \tt = t_1 + t_2 = 1.4 + 10 = 11.4 \: s$

$\therefore$ In 11.4 s the splash heard by a person on the top of the tower from the time of dropping the stone.