Explain why it isn't safe for a bus to carry standing passengers on the upper Decker
Gravity is the force that gives weight to objects and causes them to fall to the ground when dropped.
Two major factors, mass and distance, affect the strength of gravitational force on an object.
The center of gravity (CG) of an object is the point at which weight is evenly dispersed and all sides are in balance.
A human's center of gravity can change as he takes on different positions, but in many other objects, it's a fixed location.
The reason why it isn't safe for a bus to carry standing passengers on the upper Decker is the same reason why tall building must have a very strong foundation during construction.
The higher the building, the stronger the foundation and the materials used in its construction are also very tough.
The logic behind these two scenario is the centre of gravity. Tall objects tend to compromise or shift centre of gravity as compared to short objects.
In a double Decker bus passengers in the upper deck are not allowed to travel standing, because if they stand the centre of gravity of the system of the bus and all the passengers shifts to some more height.
It affects the stability which leads the bus with the passengers to fall down.
The centre of gravity of a Decker bus is supposed to be at the bottom centre of the bus within its tyres just a point at which the upper and lower decker weight is balanced.
If people are allowed to stand on the upper decker, they will compromise the centre of gravity of the bus by shifting it into another area or height and if that area is on some front or rear tyre and it bursts, the bus may fall down causing deaths.