Am elastic material has a length of 36cm when a load of 4...
Am elastic material has a length of 36cm when a load of 40N is hung on it and a length of 45cm when a load of 60N is hung on it. The original length of the string is
12cm
20cm
18cm
15cm
Correct answer is C
For Hooke's law F = Ke
⟹F/e=Kf1/e1=f2/e2Let the original length=t0thereforee1=(36−t0)cm;e2=(46−t0)cmif f1=40Nf2=60NThen 4036−t0=6045−t0⟹40(45−t0)=60(36−t0)therefore 1800−40t02160−60t060t0−40t0=2160−180020t0=360t0=18cm