Question

A spring balance is a simple device consisting of a coiled spring which gets stretched when a load is hanged at its lower end. Stretching of spring is measured by a pointer moving on a graduated scale. The reading on scale gives the magnitude of force. Now a string is tied around a wooden block and is pulled by a spring balance as shown in figure. (d) If now an additional weight is put on the block what change will you observe in reading of spring balance? Why?

Answer 1

Explanation:

SPRINGS

The predictable and repeatable way in which springs stretch in response to applied forces provides a method for measuring weight and other forces. Furthermore, springs can be designed to produce conveniently measurable stretch distances for a wide variety of forces. For example, if you were pull on each end of a steel wire that had the same diameter as a human hair, you would not be able to noticeably stretch the wire. However, if that rod were formed into a spring, then you could stretch the spring with your bare hands.

The force exerted on a stretched spring determines how far it stretches. (a) This spring has a length x when not stretched. (b) The resistance of the spring to deformation causes a force, Frestore to be exerted back on whatever is pulling on the hook. (c) A spring scale is one device that uses a spring to measure force. Image Credit: OpenStax University Physics

[1]

Springs follow Hooke's Lawwhich states that the restoring force, FR exerted by the spring is equal to the stretch or compression distance, known as the displacement (Δx), multiplied by spring stiffness (k) and the direction of the force is opposite to the direction of the displacement.

(1) \begin{equation*} \bold{F_R} = -k \bold{\Delta x} \end{equation*}

A higher spring stiffness means the spring shows a greater resistance to stretching or compressing. Spring stiffness is often called the spring constant. The negative sign tells us that the restoring force provided by the spring always points in the opposite direction as the displacement.

Check out this simulation of Hooke's Law: