experiment to determine mass of glass block using a physical balance.
Answers
Aim
To determine the mass of two different objects (here Glass box) using a beam (physical) balance.
Apparatus
physical balance, weight box, forceps, two objects of different masses.
Theory
A physical balance determine the gravitational mass of a body by making use of principle
of moments.
Load x load arm = effort x effort arm
m1g x a1: m2g x a2
m1a1 = m2a2
A body having gravitational mass m1 is placed in the left pan and a standard weight of gravitational mass m2 is put in the right pan to keep the beam horizontal for a beam balance, a1= a2
Then, m1= m2
i.e., gravitational mass of the body in left pan = gravitational mass of the standard weight in right pan.
Procedure
1. Adjust the physical balance. When the beam is in raised position, the pointer will stay at rest and coincide to the zero division or moves to and fro over the scalp, equally, about the zero division.
2. When the beam is in rest position, put any one of the object in the left pan. Now put some standard weight with the half of forceps from the weight box.
Shut the front glass door so that air current should not disturb. Raise the beam with the helf of handle and notice that beam is horizontal and pointer is moving to and fro equally both sides of zero division.
If, not, then put or remove some fractional weights to get the correct horizontal position of beam and pointer. Bring the beam in rest position and collect all the weight and add them which give the gravitational mass of the object. Now the remove the object also from left pan.
3. Repeat the Step-2 for the second object.
Result
The gravitational mass of the bodies are:
(i) mass of one body, m1 =………….g
(ii) mass of other body, m2 = …………g.
Precautions
1. Put the weight and an body in pans gently with the help of forceps.
2. Close the front glass door gently while taking the measurement so that air current should not disturb the weighing.
3. Pointer should coincide to the zero mark or oscillate equally on both side the central mark.
Sources of error
1. Air can disturb the weighing.
2. Pointer can oscillate unequally about the zero mark.