# Pressure of solids – problems and solutions

1. Mass and volume of four blocks below are same. Which is the smaller pressure exerted by block on the floor?

Solution

P = F / A

Based on this formula it is concluded that pressure (P) is directly proportional to force (F) and inversely proportional to surface area (A).

The larger the force, the larger the pressure. The larger the surface area, the smaller the pressure.

Based on the picture, the largest surface area in contact with the floor is object III, so the pressure of object III on the floor is the smallest

2. If the mass of the four triangles below is the same, the greatest pressure on the floor is shown by the image …

Solution

P = F / A = w / A

*P = **pressure**, F = **force**, w = **weight**, A = **surface area*

Based on this formula it is concluded that pressure (P) is directly proportional to force (F) and inversely proportional to surface area (A).

The larger the force, the larger the pressure. The larger the surface area, the smaller the pressure.

The smallest surface area has the greatest pressure.

3. The greatest pressure is shown by image …

Solution

P = F / A = w / A

*P = **pressure**, F = **force**, w = **weight**, A = **surface area*

Based on this formula it is concluded that pressure (P) is directly proportional to force (F) and inversely proportional to surface area (A).

The larger the force, the larger the pressure. The larger the surface area, the smaller the pressure.

The smallest surface area has the greatest pressure.

4. The force of 500 Newton works on a surface of 2.5 m^{2}. Determine pressure.

__Known :__

Force (F) = 500 Newton

Surface area (A) = 2.5 m^{2}

__Wanted :__ Pressure (P)

__Solution :__

Pressure (P) :

P = F / A

P = 500 / 2.5

P = 200 N/m^{2}

P = 200 Pascal

5. Mass of a box = 75 kg and acceleration due to gravity (g) = 10 m/s^{2}. Determine the pressure on the floor.

__Known :__

Mass (m) = 75 kg

Acceleration due to gravity (g) = 10 m/s^{2}

Weight (w) = m g = (75 kg)(10 m/s^{2}) = 750 kg m/s^{2} = 750 Newton

Surface area (A) = 6 meters x 5 meters= 30 m^{2}

__Wanted :__ Pressure on the floor

__Solution :__

P = F/A = w/A = 750/30 = 25 N/m^{2}

6. Mass of a box is 24 kg. Acceleration due to gravity is 10 m/s^{2}. Determine the pressure on the floor.

__Known :__

Mass (m) = 24 kg

Acceleration due to gravity (g) = 10 m/s^{2}

Weight (w) = m g = (24 kg)(10 m/s^{2}) = 240 kg m/s^{2 }= 240 Newton

Surface area (A) = 1 m x 0.4 m = 0.4 m^{2}

__Wanted :__ The pressure on the floor

__Solution :__

P = F / A = w / A

*P = **pressure**, F = **force**, w = **weight**, A = **surface area*

Pressure on the floor :

P = 240 N / 0.4 m^{2} = 600 N/m^{2}