Question

There is some water in the beaker placed on the pan of a spring balance. If we dip our finger in the water without touching the bottom of the beaker, then how does the reading of spring balance change?

• A. The reading decreases
• B. The reading increases
• C. The reading increases twice
• D. The reading remains unaffected

Answer 1

The correct option is B

The reading increases

When we dip our finger in the water, the water exerts upward thrust on the finger (Archimedes's principle). Due to Newton's 3rd law of motion, the finger will exert an equal and opposite force on the water in downward direction resulting in increase of the weight of water. Thus the reading of the spring balance will increase.