单选题
题目：On a 60km track, a train travels the first 30km at 30km/h. How fast must it travel the next 30km to average 40km/h for the entire trip?

单选题
题目：A body travels from A to B at 40m/s and from B to A at 60m/s. Calculate the average speed.

单选题
题目：A jet plane starts from rest with an acceleration of 3m/s² and makes a run for 35s before taking off. What is the minimum length of the runway?

单选题
题目：A train is under a journey of several hundred kilometers. How can it be regarded?

单选题
题目：Displacement is a scalar quantity.

单选题
题目：What is the acceleration of a bus approaching a bus stop?

单选题

题目：Which of the following can be regarded as an example for three dimensional motions?

单选题
题目：A car is moving along a zigzag path on a level road. This is an example for which of the following?