2. (1) A piece of rubber is 50 cm long when a weight of 35 N hangs from it and is 85 cm long when a weight
of 70 N hangs from it. What is the spring constant
of this piece of rubber?

Answer

By F = -kx {-ve just indicating the sign of the force}

=>35 = k x (85-50) x 10^-2

=>k = 100 N/m

Again by F = -kx

the answer would be c

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement