A girl stands 170 m away from a high wall and claps her hands at a steady rate so that each clap coincides with the echo of the one before. a) If she makes 60 claps in 1 minute, what value should be the speed of sound in air? b) Now, she moves to another location and finds that she should now make 45 claps in 1 minute to coincide with successive echoes. Calculate her distance for the new position from the wall.

As per the given condition in the question we can list some data as,

distance d = 170 m

To find a) speed v = ? 

             b) distance d= ?

Solution -

a) girl makes 60 claps in one minute 

hence she makes 1 clap in 1 sec 

therefore we can say that 

in 1 sec the sound travel to the wall and comes back i.e it travels a distance equal to 2d means 340m 

hence speed v = distance / time 

v = 340/1 = 340m/s

b) now she is at some another location ,

let d be the distance between the girl and the wall 

now she makes 45 claps in 1 minute

i.e 45 claps in 60 sec

1 clap in 60/45 sec i.e 1.333 sec

hence we can say in 1.333 sec the sound travel to the wall and comes back i.e it travels a distance equal to 2d

distance = speed x time

2d = 340 x 1.333 = 453.22 m 

therefore d = 453.22/2 = 226.61 m