A metal plate 80 cm long and 40 cm wide lies on the table. Calculate the mass of the slab if it exerts 4 kPa pressure on the table.

Given:
a = 80 centimeters = 0.8 meters – the length of the metal plate;
b = 40 centimeters = 0.4 meters – the width of the metal plate;
g = 10 Newton / kilogram – acceleration of gravity;
P = 4 kPa = 4000 Pascal – the pressure exerted by the metal plate on the table.
It is required to determine m (kilogram) – the mass of the metal plate.
Assuming that the slab has the geometric shape of a rectangle, we find the area of ​​the base:
s = a * b = 0.8 * 0.4 = 0.32 m2.
Then the force of gravity acting on the plate will be equal to:
F = P * s = 4000 * 0.32 = 1280 Newton.
The mass of the slab will be equal to:
m = F / g = 1280/10 = 128 kilograms.
Answer: the mass of a metal plate is 128 kilograms.