A WOODEN BLOCK OF MASS 8KG IS TIED TO A STRING ATTACHED TO THE BOTTOM OF THE TANK EQUILIBRIUM THE BLOCK IS COMPLETELY IMMERSED IN WATER .IF THE RELATIVE DENSITY OF WOOD IS 0.8 AND G =10M/S² THEN WHAT IS THE VAUE OF TENSION IN THE STRING .

Given:

 Mass of the wooden block, m= 8kg

 Relative density of wood = 0.8

We know that: 

 

The upthrust experienced by the wooden block upward will be balanced by the weight of the wooden block acting downwards + the tension on the string

i.e. Upthrust = Weight + Tension

Therefore the tension on the string = Upthrust - Weight

The upthrust experienced by the wooden block = Volume of water displaced by the block × Density of water × g

 

 

 

Tension on the string = Upthrust - Weight

                              = 100 N - (8 ×10) N

                              =20 N

Therefore Tension on the sring = 20N