Question

Take a spring of medium stiffness, about 20 cm in length. Fix the upper end of the springto a rigid support. On the lower end attach a scale pan of known mass so that the systemhangs vertically. Pull the pan 1-2 cm downwards and release. The pan will oscillate upand down. Measure the time of 20 oscillations with the help of a stop watch and calculatethe time period of oscillation of pan. Now place a middle size pebble on the pan, set it inoscillations and determine the time period of oscillation again. Calculate the mass of thepebble using the data obtained from your observations.

Answer 1

Maximum mass that the scale can read, M = 50 kg

Maximum displacement of the spring = Length of the scale, l = 20 cm = 0.2 m

Time period, T = 0.6 s

Maximum force exerted on the spring, F = Mg

where,g = acceleration due to gravity = 9.8 m/s2

F = 50 × 9.8 = 490 N

∴spring constant, k = F/l = 490/0.2 = 2450 N m-1.

Mass m, is suspended from the balance  

∴Weight of the body = mg = 22.36 × 9.8 = 219.167 N

Hence, the weight of the body is about 219 N.

Answer 2

I believe your answer is not apt, as the question demands an answer in Kg as that is the unit of mass