To solve this problem, we will start by defining each of the variables given and proceed to find the modulus of elasticity of the object. We will calculate the deformation per unit of elastic volume and finally we will calculate the net energy of the system. Let's start defining the variables
Yield Strength of the metal specimen

Yield Strain of the Specimen

Diameter of the test-specimen

Gage length of the Specimen

Modulus of elasticity



Strain energy per unit volume at the elastic limit is



Considering that the net strain energy of the sample is




Therefore the net strain energy of the sample is 
Answer:
Magnitude of the net force acting on the kayak = 39.61 N
Explanation:
Considering motion of kayak:-
Initial velocity, u = 0 m/s
Distance , s = 0.40 m
Final velocity, v = 0.65 m/s
We have equation of motion v² = u² + 2as
Substituting
v² = u² + 2as
0.65² = 0² + 2 x a x 0.4
a = 0.53 m/s²
We have force, F = ma
Mass, m = 75 kg
F = ma = 75 x 0.53 = 39.61 N
Magnitude of the net force acting on the kayak = 39.61 N
Wavelength, because of how it lengths out from the rest.
No becuase the simplified case of constant speed, use the formula:
<span>distance = speed x time</span>