Introduction:
In order to find the force between two blocks lying 1m apart, we need to consider the gravitational force acting between the two blocks. The force of gravity is determined by the masses of the objects and the distance between them.

Given data:
- Mass of each block: 40 kg
- Distance between the blocks: 1 m

Calculating the force:
To calculate the force between the two blocks, we can use Newton's Law of Universal Gravitation, which states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Formula:
The formula for calculating the force of gravity is:

F = G * (m1 * m2) / r^2

where:
F is the force of gravity,
G is the gravitational constant (approximately 6.67430 x 10^-11 N m^2/kg^2),
m1 and m2 are the masses of the objects, and
r is the distance between the centers of the objects.

Substituting the given values:
In this case, we have two blocks with equal masses (m1 = m2 = 40 kg) and a distance of 1 meter (r = 1 m). Let's substitute these values into the formula:

F = (6.67430 x 10^-11 N m^2/kg^2) * (40 kg * 40 kg) / (1 m)^2

Simplifying the equation:
Calculating the values within the parentheses first:

F = (6.67430 x 10^-11 N m^2/kg^2) * (1600 kg^2) / 1 m^2

F = 6.67430 x 10^-11 N * 1600 kg

F = 1.067888 x 10^-7 N

Result:
Therefore, the force between the two blocks lying 1m apart, with each block having a mass of 40kg, is approximately 1.067888 x 10^-7 Newtons.