Question
Sat March 14, 2015 By: Srivathchava15

A block of wood is kept on a table top . The mass of wooden block is 5kg and its dimension are 40cm*25cm*10cm. Find pressure extended

Expert Reply
Faiza Lambe
Sat March 14, 2015
Given:
Mass of the wooden block= 5 kg
Dimensions = 40 cm x 25 cm x 10 cm
The weight of the wooden block applies a thrust on the top of the table.
Thrust = F = m x g
                = 5 kg x 9.8 m s-2
                = 49 N
Considering the sides of dimensions, 
(a) 25 cm x 10 cm
(b) 40 cm x 25 cm
 
(a) When the block lies on its sides of dimensions 25 cm x 10 cm
 
Area of a side = length x breadth
                          = 25 cm x 10 cm = 250 cm2 = 0.025 m2
Therefore,
begin mathsize 14px style Pressure equals Thrust over Area
space space space space space space space space space space space space space space equals fraction numerator 49 space straight N over denominator 0.025 space straight m squared end fraction space space space
space space space space space space space space space space space space space space equals 1960 space straight N space straight m to the power of negative 2 end exponent end style
 
The pressure exerted by 25 cm x 10 cm is 1960 N m-2.
 
(b) When the block lies on its sides of dimensions 40 cm x 25 cm
 
Area of a side = length x breadth
                       = 40 cm x 25 cm = 1000 cm2 =  0.1m2
Therefore,
begin mathsize 14px style Pressure equals Thrust over Area
space space space space space space space space space space space space space space equals fraction numerator 49 space straight N over denominator 0.1 space straight m squared end fraction
space space space space space space space space space space space space space space equals 490 space straight N space straight m to the power of negative 2 end exponent end style
 
The pressure exerted by 40 cm x 25 cm is 490N m-2.
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