If an object moves with constant velocity, then which one of the following statement is not correct?

Solution (By Examveda Team)

First, what does "constant velocity" mean? It means the object is moving at a steady speed AND in a steady direction.

Let's look at each option:

Option A: Its motion is along a straight line
If the velocity is constant (steady speed and direction), the object *must* be moving in a straight line. If it curved, the direction would be changing, and thus the velocity wouldn't be constant. So, this statement IS correct.

Option B: Its speed changes with time
If the velocity is *constant*, the speed *cannot* change. The speed is staying the same. So, this statement is NOT correct, and likely our answer.

Option C: Its acceleration is zero
Acceleration is the rate of change of velocity. If the velocity isn't changing (it's constant), then the acceleration is zero. So, this statement IS correct.

Option D: Its displacement increases linearly with time
Displacement is the change in position. If you're moving at a steady speed in a straight line, the distance you cover (displacement) increases at a steady rate. That's what "linearly" means. So, this statement IS correct.

Therefore, the answer is Option B: Its speed changes with time. Because with constant velocity, the speed cannot change.