Which of the following statements are not correct? <br>
1. If the speed-time graph is a straight line parallel to time axis, then it indicates that the object is moving with uniform speed <br>
2. The area below the velocity-time graph gives the distance covered by the object.<br>
3. Acceleration is taken as positive if it is in the direction opposite to the direction of velocity.<br>
4. The velocity-time graph for non-uniformly accelerated motion is always a straight line.
