Page 161 - Volt Elevate The World Around Us Book 4

the object and the density of water. If the object is less dense than water, it floats. If the

object is denser than water, it sinks. This floating and sinking also depends on a force
called buoyant force, which is the upward push water gives to objects.

Floating Objects

Objects float in water when they are
lighter or less dense than water. For

example, a wooden stick, a piece of
plastic or a dry leaf will float easily. Some
objects float even if they are very large.

An example is a ship made of iron. Even air balloon floats on ship floats on water
though iron is dense, the ship is made water
hollow and filled with air spaces, making its overall density less than water. This allows

the ship to float and carry heavy loads across the sea.

Sinking Objects

Objects sink in water when they are heavier or denser than water.

For example, a stone, an iron nail or a coin will sink if dropped
into a bucket of water. These objects do not get enough upward
push from water to balance their weight, so they go down. coins sink in water

Smart Stack

A small stone sinks quickly, but a huge iron ship floats easily. This is because the shape of the ship
allows water to push it upwards more strongly.
Remember

Mind Refresh

Water is essential for __________. Living beings use it for several __________. __________ is the
main source of water on the earth. Other sources of water are __________ water and __________
water. Rivers can be __________ -fed or __________ -fed. Water from natural sources is unfit for
__________. Dams, reservoirs and __________ are built to store and use river water. The change

of water to __________ on heating is called evaporation. __________ is the change of water
vapour to water on cooling. The change of water to water vapour and back to water in nature is
called __________. The materials around us, both natural and man-made, have properties like
__________, mass and __________. Weight depends on gravity, while __________ is constant
everywhere. __________ explains why some objects are heavier or lighter for their size. Objects
__________ if less dense than water and __________ if denser, due to buoyant force.

Apply

151