Question about the Movie "Speed"?

When you were swung in a circle as a child, by your arms, you felt not only dizzy, but your arms being pulled hard. In physics, this is because your velocity was changing direction. If someone let go of your arms, you would no longer feel the pulling, but you would fly straight, no longer in a circle.

Likewise when the bus enters the turn, and then goes straight again. The sharper and faster the turn, the faster the change in direction. The bus responds by tipping because the bus is tall. In a low car, you still slide across the seat, but you probably are not afraid of the car tipping. This is one reason they say SUVs are no safer than cars (even though they are bigger), because they tip over easier. This has to do with the center of gravity. The higher the center of gravity, the easier to tip. A car may still "spin out" in a sharp turn, but that is safer than tipping!

Now one way to help an object from tipping in one direction is to change the center of gravity. This can be done by lowering the mass, or moving mass to one side... If a box was in the wind, and you put a brick in the box, the best place to put the brick would be at the bottom of the box, and on the side towards the wind.

For the bus, all the passengers should climb in the seat against the window, even two in a seat. This is why all circular ramps on a highway are tilted in... this has the effect of leaning the vehicle in which reduces tipping as well as reducing spin-outs. I imagine the bus was going too fast for the turn, so it was time to take "extreme" measures to prevent the tipping.

Of course, this is what you do on a bike when you take a turn, you "lean into the turn". Try turning your bike without "leaning in first... you will immediately tip over. This is related.

Well, I hope all this rambling helps a bit.

Okay, you know vectors? And you know Newton's laws, right?

The bus has forward vector. And as an object in motion it will tend to stay in motion in the same direction unless acted on by an outside force.

When they turn the wheels hard right, the bottom of the bus will move to the right (right vector) but the top of the bus will attempt to continue in its original direction on a straight line. When you add those two, what happens is the right wheels lift.

They're attempting to add weight to the right side to keep it down. (Adding some down vector from the acceleration due to gravity.)