Posted by **lau** on Monday, May 24, 2010 at 12:43am.

A soccer player kicks a rock horizontally off a 41.7 m high cliff into a pool of water. If the player hears the sound of the splash 3.08 s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s.

- physics -
**drwls**, Monday, May 24, 2010 at 6:13am
Use the height of the cliff to predict the time to fall, t1.

t1 = sqrt (2H/g)= 2.917 s

The delay time to hear the splash

t2 = 3.08 - 2.917 s,

tells you how far away it hits the water, S = t2*343 = 55.9 m

which is a combination of vertical and horizontal displacement, H and X. Use the Pythagorean theorem

S^2 = H^2 + X^2

to get the horizontal displacement when the ball hits the water:

X = sqrt[(55.9)^2 - (41.7)^2] = 37.2 m

The initial speed of the rock, which was horizontal, equals X divided by the fall time, t1.

## Answer This Question

## Related Questions

- physics - a soccer player kicks a rock horizontally off a 40.0-m-high cliff into...
- physics - A soccer player kicks a rock horizontally off a 40.0 m high cliff into...
- physics - A soccer player kicks a rock horizontally off a cliff 42.9 m high into...
- physic - Question Part Points Submissions Used A soccer player kicks a rock ...
- Physics - A soccer player kicks a rock horizontally off the a 40 m high cliff ...
- physics - Soccer player #1 is 7.31 m from the goal, as the figure shows. If she ...
- physics - Soccer player #1 is 7.31 m from the goal, as the figure shows. If she ...
- physics - Soccer player #1 is 8.6 m from the goal. If she kicks the ball ...
- Physics - A soccer player kicks a rock with an initial velocity of 0.50 m/s from...
- physics - To estimate how high the cliff is you throw a rock off the edge and 7....

More Related Questions