Question

A pressure of 1000 Pa, acts on a surface of area 15 cm2 by a block of mass ‘m’. Calculate ‘m’. Calculate the new pressure exerted by the same block if the area of
contact with the surface becomes 10 cm2.

Answer 1

When a block of mass m is kept on a surface of area A = 15 cm², the weight acts on the surface, resulting in a pressure P.

   Force = m g = P * A
           m = 1000 Pa * 15 *10⁻⁴ m² / 10 m/sec²
               = 0.15 kg

 The block rests now on a smaller surface area.  So the weight of the block = m g acts (is spread) on the new surface area =>

          Pressure = 0.15 kg * 10 m/s² / [ 10 * 10⁻⁴  m² ]
                        = 1, 500 Pa