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**Definitions**:

- The
**density**( ) of an object of total mass*M*and volume*V*is given by:= . (5) ^{3}. - The
**specific gravity**of a substance is the ratio of the density of the substance to the density of water ( = 1`x`10^{3}*kg*/*m*^{3}). -
**Pressure**: When an object is immersed in a fluid or gas, it experiences a uniform inward force over its entire surface, due essentially to the weight of the fluid sitting on top of it. The**pressure**on the object is defined to be the force per unit area:*P*= .(6) *Pa*) where:1 *Pa*= 1*N*/*m*^{2}.(7)

**Note: **At the earth's surface, the pressure felt by an object
due to the weight of the atmosphere above it is:

1 atmosphere = 1.01 x 10^{5} Pa.
| (8) |

10/9/1997