A physical problem in sports One elevator, with acceleration of 2 when starting, with acceleration of - 1 when braking, and building height of 52m The elevator first speeds up, then rises at a constant speed, and finally decelerates at a constant speed. What is the maximum speed of 16 seconds when the elevator is used in the whole process?

A physical problem in sports One elevator, with acceleration of 2 when starting, with acceleration of - 1 when braking, and building height of 52m The elevator first speeds up, then rises at a constant speed, and finally decelerates at a constant speed. What is the maximum speed of 16 seconds when the elevator is used in the whole process?

Let me first give my answer: the maximum speed is 4m / s, the acceleration time is 2S, the deceleration time is 4S, and the uniform speed time is 10s. In addition, my idea. When I encounter this type of segmented motion, I can consider using the image method to do it. Please draw a V-T image according to the conditions given by the topic, and you will get a trapezoid

A static object with a mass of 2kg is pushed by a horizontal force of 18N. It moves 10 meters in 2 seconds. How far can it move when the thrust is removed

Let the friction force on the ground be f, so when the object is pushed by 18N, the resultant force F = 18-f, the acceleration a = (18-f) / M = (18-f) / 2 starts to move from rest, so 1 / 2A * 2 * 2 = 10 is brought into the expression of a in 2 seconds, and the solution of 1 / 2 * (18-f) * 2 * 2 / 2 = 10 is obtained, and the friction force F = 8N