To determine the mass of two different objects using a beam balance ( 7 Stone Physical Beam Balance)

APPAARTUS SUPPLIED WITH THIS EXPERIMENT

1. PHYSICAL BEAM BALANCE SEVEN STONE
2. WEIGHT BOX WITH FRACTIONAL WEIGHTS ( 200gms )
3. OPERATING MANUAL

Physical beam balance is an instrument used to measure the mass of the body. It works upon the principle of moments i.e. when the body is in equilibrium under the action of force the sum of clockwise moments is equal to the sum of anticlockwise moments. 

There are glass doors provided to the wooden box to avoid the air disturbance and to protect the balance from dust particles present in the air. It consists of a metal beam B with a knife-edge at the centre pointing in the downward direction. The knife-edge rests on a horizontal flat top made of hard material (Brass). There are two edges with nuts n1 and n2 at the two ends of the metal beam. A pair of pans P1 and P2 are suspended through stirrups S1 and S2 respectively. The nuts n1 and n2 are used to adjust the weights of the pan. In the middle of the beam, there is a long pointer P pointing in the downward direction. This pointer moves on an ivory scale G fixed at the bottom of the brass pillar V. The pillar has two supports K1 and K2 which rests the metal beam when not in use. A knob H, at the bottom of the wooden box, is connected by a horizontal rod to the vertical pillar V. When the handle is rotated rightwards, the beam is raised and is ready to use.