Answer:
W=35955 N
Step-by-step explanation:
In an elastic material like steel when deformation takes place then the stress ( σ ) produced in the material is directly proportional to the strain ( ∈

therefore young modulus=stress/strain
y=σ/∈
y

f=external force
A is the cross-sectional area
L is the original length
Δ L is the elongation
young modulus of steel 200 Gpa


200*10^9=f/1.41/(5.1*10^-7/4)
f=200*10^9*1.41*(5.1*10^-7/4)
f=35955 N
which is equal to the weight of the body