Activity 10.4 Class 9 Science Gravitation

Activity 10.4 Class 9 Science Gravitation Chapter 10

What Activity asks?

  • Activity 10.4 asks us to push a plastic bottle in the water and check the force needed to push it further. 
  • What happens when we release the submerged bottle.
  • does gravitational attraction also apply to the plastic bottle?


  • Plastic bottles float on the water. We require some force to immerse it into the water; this force increases with the depth of the water.
  • When we release the bottle it comes to the surface and floats there.
  • Gravitation work on every object every time.


Earth attracts water molecules also. As result water molecules also want to go near the core of the earth. When we immerse a water bottle it displaces some water molecules. If the force of the displaced water is lesser than the gravitational attraction force of the bottle, we need not need to apply external force e.g. stone/heavy particles. But, with plastic bottles, it does not happen so. The volume of displaced water is higher than the mass of the bottle. As a result, we need external pressure to immerse the bottle.

As we go deeper into the water, the upward pressure on the bottle increases due to the increase in the pressure of water. As a result, we need more force to submerge the bottle further.

Next: Activity 10.5 Class 9 Science Gravitation.

See also: Activity 10.3 Class 9 Science Gravitation.


Ref: Chapter 10.

Activity 10.4 Class 9 Science Gravitation Chapter 10


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