Q21 of 31 Page 143

The volume of 50 g of a substance is 20 cm3. If the density of water is 1 g cm-3, will the substance float or sink?

Given,

Mass of substance = 50 g


Volume of substance = 20 cm3


We know that,


Density of substance =


=


= 1.42 g cm-3


Clearly, the density of packet is more than the density of water. Therefore, it will sink. The packet which sinks in water will displace water equal to its own volume.


Given,


Volume of packet = 350 cm3


So, it will displace 350 cm3 of water.


Now we have now to calculate the mass of 350 cm3 of water.


Density of water =


1 g cm-3 =


Mass of water = 1 g cm-3 × 350 cm3


= 350 g


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A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.

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