Answer:

Explanation:
Net force by which man push the lawn mower is given as

now it is given that 37% of this force is vertically downwards
so we will have


now we also know that

here we have


Now work done by this force to move the lawn mower is given as



The motor bike can travel 225 kilometers on 5 liters of petrol
Answer:
The correct answer is d
Explanation:
In this exercise they ask us which statement is correct, for this we plan the solution of the problem, this is a Doppler effect problem, it is the frequency change due to the relative speed between the emitter and the receiver of sound.
The expression for the Doppler effect of a moving source is
f ’= (v / (v- + v_s) f
From this expression we see that if the speed the sound source is different from zero feels a change in the frequency.
The correct answer is d
Answer
The answer and procedures of the exercise are attached in the following archives.
Step-by-step explanation:
You will find the procedures, formulas or necessary explanations in the archive attached below. If you have any question ask and I will aclare your doubts kindly.
That type of bending is called "diffraction" of waves.