Question

A half meter ruler is suspended by a thread from the mid point of the ruler. It balance horizontally when a 50 gram and unknown mass m are suspended respectively from 10 centimetre and 45 centimetre. Calculate the unknown mass?

Answer 1

hope u understand the calculations yourself

Answer 2

Answer:

Unknown mass is $50 g$

Explanation:

From the principle of moments, Clockwise moment = Anticlockwise moment 100g × (50 − 40) cm = m × (40 − 20) cm 100g × 10 cm = m × 20 cm = m = 50 g

(ii) The rule will tilt on the side of mass m (anticlockwise) if the mass m is moved to the mark 10cm.

(iii) Anticlockwise moment if mass m is moved to the mark 10 cm = 50g × (40−10)cm = 50 × 30 = 1500 g cm Clockwise moment = 100g × (50 − 40) cm = 1000g cm Resultant moment = 1500g cm − 1000g cm = 500g cm (anticlockwise)

(iv) From the principle of moments, Clockwise moment = Anticlockwise moment To balance it, 50g weight should be kept on the right-hand side too produce a clockwise moment. Let its distance from the fulcrum be d cm. Then, 100g × (50 − 40) cm + 50g × d = 50g × (40 − 10)cm 1000g cm + 50g × d = 1500 g cm 50 g × d = 500g cm So, d =10 cm By suspending the mass 50g at the mark 50 cm, it can be balanced.