When a particle's position changes, which of the following statements is true about its displacement and the distance it covers?
| 1. | Both cannot be zero. |
| 2. | Either one can be zero. |
| 3. | Both must be zero. |
| 4. | If one is positive, the other is negative, and vice-versa. |
| 1. | zero |
| 2. | constant |
| 3. | proportional to time |
| 4. | proportional to displacement |
| 1. | \(1~\text{ms}^{-1}\) | 2. | \(2~\text{ms}^{-1}\) m/s |
| 3. | less than \(1~\text{ms}^{-1}\) | 4. | greater than \(2~\text{ms}^{-1}\) |
A boy throws a ball straight up the side of a building and receives it after \(4~\text s.\) On the other hand, if he throws it so that it strikes a ledge on its way up, it returns to him after \(3~\text s.\) The ledge is at a distance \(d\) below the highest point, where \(d=? \) (take acceleration due to gravity, \(g=10~\text{ms}^{-2})\)
1. \(5~\text m\)
2. \(2.5~\text m\)
3. \(1.25~\text m\)
4. \(10~\text m\)
Mark the correct statements for a particle going on a straight line:
| (a) | if the velocity and acceleration have opposite sign, the object is slowing down. |
| (b) | if the position and velocity have opposite sign, the particle is moving towards the origin. |
| (c) | if the velocity is zero at an instant, the acceleration should also be zero at that instant. |
| (d) | if the velocity is zero for a time interval, the acceleration is zero at any instant within the time interval. |
Choose the correct option:
| 1. | (a), (b) and (c) | 2. | (a), (b) and (d) |
| 3. | (b), (c) and (d) | 4. | all of these |
A stone is released from an elevator going up with an acceleration \(a.\) The acceleration of the stone after the release is:
1. \(a\) upward
2. \((g-a)\) upward
3. \((g-a)\) downward
4. \(g\) downward