The force that acts on all objects, all the time on Earth is gravitational force.
The force that surface exert on an object perpendicularly is normal reaction.
<h3>What force acts on all objects, all the time on Earth?</h3>
- Force due to gravity is gravitational pull on objects due to its position on earth's surface.
The force due to gravity on object's is calculated by applying Newton's second law of motion as follows;
F = mg
where;
- m is the mass of the object
- g is acceleration due to gravity
The force that surface exert on an object perpendicularly is normal reaction.
Thus, the force that acts on all objects, all the time on Earth is gravitational force.
Learn more about force of gravity here: brainly.com/question/2537310
Answer: 
Explanation:
Given
Water column height 
After oil is poured, the total height becomes 
Pressure at the bottom will be the sum due to the water and oil column
Suppose the density of the oil is 
Pressure at the bottom
![\Rightarrow P=10^3\times g\times 25+900\times g\times 15\\\Rightarrow P=100g[250+135]\\\Rightarrow P=3773\times 100\ Pa\\\Rightarrow P=377.3\ kPa](https://tex.z-dn.net/?f=%5CRightarrow%20P%3D10%5E3%5Ctimes%20g%5Ctimes%2025%2B900%5Ctimes%20g%5Ctimes%2015%5C%5C%5CRightarrow%20P%3D100g%5B250%2B135%5D%5C%5C%5CRightarrow%20P%3D3773%5Ctimes%20100%5C%20Pa%5C%5C%5CRightarrow%20P%3D377.3%5C%20kPa)
