Tuesday 19 September 2017

Gravitation

Gravitation

Gravitation

Questin 1. Why is it difficult to hold a school bag having a strap made of a thin and strong string?
Answer: The force exerted by a thin and strong string is distributed to very less area and hence the force applied due to the bag is more, the pressure exerted on the body by thin straps will be more and hence will be more painful.
As pressure is inversely proportional to area, if the area is reduced pressure
ncert-solutions-for-class-9-science-gravitation-1.

Questin 2. What do you mean by buoyancy?
Answer: The upward force exerted by any fluid (liquid, gas) on an object is known as upthrust or buoyancy.

Questin 3. Why does an object float or sink when placed on the surface of water?
Answer: The density of the objects and water decides the floating or sinking of the object in water.
The density of water is 1 gm/cm3.
  • If the density of an object is less than the density of water then the object will float.
  • If the density of an object is more than the density of water then the object will sink.

GRAVITATION

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