Why an iron nail sinks when placed on surface of water?
Answer & explanation
Correct answer: option 1
When an iron nail is placed on the surface of water, it sinks into water.
The force due to the gravitational attraction of the earth on the iron nail pulls it downwards. There is an upthrust of water on the nail, which pushes it upwards. But the downward force acting on the nail is greater than the upthrust of water on the nail. So it sinks.