Question

The figure shows a brick of weight 2 kgf and dimensions 20 cm × 10 cm × 5 cm placed in three different positions on the ground. Find the pressure exerted by the brick in each case.

Answer 1

(a) Weight of bricks = Thrust = F = 2 kgf

Area of base = `20/100 xx 10/100 = 1/50 "m"^2`

Pressure exerted P = `"F"/"A" = "2 kgf"/(1/50 "m"^2) = 100  "kgf m"^-2`

Or

Area of base = area of top L × B

20 cm × 10 = 200 cm² 

P = `"Thrust"/"A" = "2 kgf"/200 "cm"^2 = 1/100 = 0.01 "kgf  cm"^-2`

(b) 

area of base = area of top

= 5 cm × 10 cm = 50 cm² 

Pressure exerted = P = `"F"/"A" = "2 kgf"/"50 cm"^2 = 0.04`

P = 0.04 kgf cm^-2 

(c) 

Weight of brick 

F = 2 kgf

Area of base = L × B

= 20 cm × 5 cm = 100 cm² 

Pressure exerted = `"F"/"A" = 2/100 = 0.02  "kgf cm"^-2 `