The largest possible displacement you can get by combining the two of them is if they're both in the SAME direction. You walk 3 meters, stop for a breath, then walk another 4 meters in the same direction as the first one. The resultant is 7 meters.
The smallest possible resultant is 1 meter, if the two displacements are in OPPOSITE directions. This time, you walk 4 meters, stop for a breath, then you TURN AROUND and walk 3 meters back in the direction you came from. You end up 1 meter from where you started.
The time described above is known as the waves Period.
The time which it takes for a particle to complete one full cycle is known as the period. Period is normally measured in seconds. Frequency on the other hand is the number of cycles which are completed in a given period of time e.g a second. periodic time T is given by reciprocal of frequency (1/f).
Answer
According the conservation of energy
I for ball = 
![v_i^2+[1+\dfrac{2}{3}]=2gh](https://tex.z-dn.net/?f=v_i%5E2%2B%5B1%2B%5Cdfrac%7B2%7D%7B3%7D%5D%3D2gh)
a) 
b) 
