Q13 of 16 Page 343

A wooden block is kept on a table top. The mass of the wooden block is 5 kg and its dimensions are 40 cm × 20 cm × 10 cm. Find the pressure exerted by the wooden block on the table top if it is made to lie on the table top with its sides of dimensions (a) 20 cm × 10 cm and (b) 40 cm × 20 cm.

Mass of wooden block = 5 kg
Dimension of the block = 40 cm × 20 cm × 10 cm
= 0.4 m × 0.2 m × 0.1 m

Force = mass × acceleration due to gravity
= 5 kg × 9.8 m/s2


= 49 N


(a) 20 cm × 10 cm


Area = 20 cm × 10 cm = 0.2 m × 0.1 m = 0.02 m2


Pressure = = = 2450 N/m2


(b) 40 cm × 20 cm


Area = 40 cm × 20 cm = 0.4 m × 0.2 m = 0.08 m2


Pressure = = = 612.5 N/m2


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