Question three is C and question 4 is b
Elastic potential energy is given by formula

here we know that


Now using above formula we have


So elastic potential energy in the chord is 14400 J
<span>The platform scale consists of a combination of third and first class levers so that the load on one lever becomes the effort that moves the next lever.Through this arrangement, a small weight can balance a massive object. If x=450 mm,determine the required mass of the counterweight S required to balance a 90-kg load, l.</span>
<em>A clamp-type measuring instrument operates on the principle of; </em>
A. induction