NCERT Solutions for Class 8th Science Chapter 5 .5 Weight and Its Measurement (Fig. 5.12) — Activity 5.9: Let us explore
Book page 735 Updated on2026-09-19
Q1.
Hang one end of the spring from a nail (Fig. 5.12a). From the other end, hang an object and observe the spring (Fig. 5.12b). Does the spring stretch?
Fig. 5.12, page 73 — (a) a hanging spring; (b) two different objects hung from the same spring.
Answer
Yes, the spring stretches as soon as the object is hung from it, and it stays stretched as long as the object hangs there.
The spring is being pulled down at its lower end. Nothing is touching the object except the spring, so the downward pull on it comes from the Earth — the gravitational force, that is, the object's weight. The stretch of the spring is simply the visible effect of that pull.
Q2.
Now hang the other objects, one by one and notice the stretch in the spring each time. Is the stretch caused by each object the same?
Answer
No. The stretch is different for different objects — the stone stretches the spring more than the pencil box, and the tiffin box stretches it by a different amount again.
The spring has not changed, so a bigger stretch can only mean a bigger pull. This indicates that the Earth pulls different objects with different forces, that is, the weight of different objects is different.
Q3.
Can we use the spring to measure the weight of an object?
Answer
Yes — and that is exactly what a spring balance is.
The stretch of the spring grows with the pull on it, so the stretch can stand in for the weight. A spring balance is a simple device used to measure weight (force). It consists of a spring fixed at one end, with a hook attached at the other end. When we hang an object from the hook, the spring stretches, and the amount of stretching gives the weight of the object. There is a scale on the balance marked to show the weight (force) in newton, and usually a second scale showing the corresponding values of mass in gram (g).
Careful: those gram markings are made on the assumption that the balance is being used on the Earth, with the Earth's gravitational force attracting the object. The instrument really measures a force; the mass scale is only a convenience.