Velocity (unit:m/s) of the wave is given with the formula:
v=f∧,
where f is the frequency which tells us how many waves are passing a point per second (unit: Hz) and ∧ is the wavelength, which tells us the length of those waves in metres (unit:m)
f=1/T , where T is the period of the wave.
In our case: f=1/3
∧=v/f=24m/s/1/3=24*3=72m
Answer:

Explanation:
Given:
mass of ice melted, 
time taken by the ice to melt, 
latent heat of the ice, 
Now the heat rejected by the Carnot engine:



Since we have boiling water as hot reservoir so:

The cold reservoir is ice, so:

Now the efficiency:



Now form the law of energy conservation:
Heat supplied:

where:
heat supplied to the engine




Now the work done:


