Aball is dropped into a pond from a height of 42.1m .the splash of sound is heard 3.13seconds after the ball is dropped determine the speed of siund. take g=9.8m/s

  Speed of sound = 210.5 m/s.

Explanation:

Initial height from ground = 42.1 meter.

We have equation of motion , , s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

In this the velocity of body in vertical direction = 0 m/s, acceleration = 9.8 , we need to calculate time when s = 42.1 meter.

Substituting

So it will take 2.93 seconds to reach ground.

Extra time taken to hear sound = 3.13 - 2.93 = 0.2 seconds

Distance travelled by sound = 42.1 m

 Speed of sound = Distance / Time = 42.1 / 0.2 = 210.5 m/s.

Speed of sound = 210.5 m/s.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

do you have a formula possibly