Question

Which of the following is/are the example(s) of one-dimensional motion?
A. motion of a vehicle in a straight line
B. motion of train on a straight railway track
C. motion of object dropped from a certain height from the ground
D. A man working on a straight path

Answer 1

Hint: In this question we have been asked to state the examples of one-dimensional motion. Therefore, we shall define one-dimensional motion. We have been given different statements defining a certain motion. We shall discuss every statement and select the statement(s) showing one-dimensional motion as our answer. We know that the motion along the straight line is known as one-dimensional motion.

Complete solution:
When an object moves in a straight line in one direction, the motion is said to be one dimensional. In one-dimensional motion the body is restricted to move in only two directions in a straight line. Therefore, the velocity and acceleration vectors can point only two directions where one direction is exactly opposite or at 180 degrees of the first.
Now, the first statement defines the motion of a vehicle moving in a straight line. Since, the vehicle is not taking any turn and moving in a straight line, the motion of the vehicle is one dimensional.
The second statement is of a train moving on a straight railway track. Since the track is straight, the motion of the train is one dimensional.
Now, the third statement describes the motion of an object dropped from a height. We know that an object falling from a height will fall under the effect of gravitational pull. The object falls in a straight line under gravitational pull. Therefore, this is also an example of one-dimensional motion.
The last statement defines the working of a man in a straight oath. Now, as the man is working along a straight line, the motion in carrying out the work is one-dimensional motion.

Therefore, all the given statements are examples of one-dimensional motion.

Note:
In one-dimensional motion, the speed is measure of how quickly the object moves along this straight line and velocity is speed with direction. However, in one-dimensional motion the direction of the body is limited to two directions for velocity and acceleration vectors to point. One direction is exactly opposite of the other.