A 400-kg concrete block is 1 m long, 0.6 m wide, and 0.3 m high. It can exert three different pressures on a horizontal surface, depending on which face it rests on. The highest pressure is
A) 0.7 kPa.
B) 2.2 kPa.
C) 13.1 kPa.
D) 21.8 kPa.

Question

Quizplus · Accepted Answer

Pressure is calculated as $P = \frac{F}{A}$, where $P$ is pressure, $F$ is the force (in this case, the weight of the block), and $A$ is the area of the surface in contact with the ground. The weight of the block is $F = mg$, where $m = 400 \, \text{kg}$ and $g = 9.8 \, \text{m/s}^2$, so $F = 400 \times 9.8 = 3920 \, \text{N}$. The highest pressure will be exerted when the block is resting on the face with the smallest area.1. For the 1 m x 0.6 m face, the area is $A = 1 \times 0.6 = 0.6 \, \text{m}^2$.2. For the 1 m x 0.3 m face, the area is $A = 1 \times 0.3 = 0.3 \, \text{m}^2$.3. For the 0.6 m x 0.3 m face, the area is $A = 0.6 \times 0.3 = 0.18 \, \text{m}^2$.The smallest area is 0.18 m², so the highest pressure is when the block rests on the 0.6 m x 0.3 m face. Calculating the pressure for this scenario: $P = \frac{3920}{0.18} \approx 21777.78 \, \text{Pa} = 21.8 \, \text{kPa}$.

A 400-Kg Concrete Block Is 1 M Long, 0