Question

QUES. A block of size 20 m x 10 m x 5 m exerts a force of 30 N. Calculate the maximum and minimum pressure exerted by block on ground.

QUES. The tip of drawing pin has an area 1.0 x 10^-8 sq. m. Find the pressure exerted if force applied is 10 N.

Answer 1

Pressure = Force/Area
 Pressure will be maximum when area will be minimum ( i.e. when 10m and 5m dimensions are under consiferation )

Max Pressure = 30/(10*5) = 3/5 N/m2

Pressure will be minimum when area will be max ( i.e. when 20m and 10m dimensions are under consiferation 

Min Presssure = 30/(20*10) = 0.15 N/m2

Answer 2

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We know, when force is constant, pressure ∞ 1/Area.Therefore, pressure is maximum when area is minimum and vice versa.

By calculating the area of three faces, we get,

⇒A₁ = (20×10)= 200 sq m.

⇒A₂ = (10×5) = 50 sq m.

⇒A₃ = (20×5) = 100 sq m.

∴ A₁ is maximum and A₂ is minimum.

∴ Minimum pressure P₁ = F/A₁ = 30/200 = 0.15 Nm⁻².

∴ Maximum pressure P₂ = F/A₂ = 30/50 = 0.6 Nm⁻². (Ans)