(original title). A middle school student is sitting on a bus with a drink in his hand. When the bus turned sharply, the drink in the cup shook out. Middle school students have a lot of complaints about drivers, so they say, "Master, how do you drive? The drink in my cup shook out. " The driver said, "My car is turning." The middle school student said, "Then how did you become so big? Turn it down, and the drink in the cup won't shake out. " In this dialogue, which of the following concepts does the middle school students lack understanding? ( )

A. inertia B. pressure C. buoyancy D. pressure

A: A.

Analysis: Inertia is only related to the mass of the object and has nothing to do with the speed of motion. Drinks can be thought of as moving in a straight line at a uniform speed. When turning, the motion state of the car changes, and the drink continues to move in a straight line at a constant speed due to inertia, so it is spilled. "Turn it down, the drink in the cup won't shake out" obviously ignores inertia.

As for the size of the turn and the degree of splashing, there is no requirement for the senior high school entrance examination.

High school requirements

Solution: centripetal acceleration a = v 2/r, and the linear velocity is the same.

Then: The smaller the turn, the bigger the centripetal acceleration, and the easier it is to make a turn.