Q. No.| Assertion (A): | For a given initial and final position the average velocity is single-valued while the average speed can have many values. |
| Reason (R): | Velocity is a vector quantity and speed is a scalar quantity. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
A particle is moving such that its position coordinates \((x,y)\) are \( (2~\text m, 3~\text m)\) at time \(t=0,\) \( (6~\text m, 7~\text m)\) at time \(t=2~\text s\) and \( (13~\text m, 14~\text m)\) at time \(t=5~\text s.\) The average velocity vector \((v_{avg})\) from \(t=0\) to \(t=5~\text s\) is:
| 1. | \(\frac{1}{5}\left ( 13\hat{i}+14\hat{j} \right )\) | 2. | \(\frac{7}{3}\left ( \hat{i}+\hat{j} \right )\) |
| 3. | \(2\left ( \hat{i}+\hat{j} \right )\) | 4. | \(\frac{11}{5}\left ( \hat{i}+\hat{j} \right )\) |
A car turns at a constant speed on a circular track of radius \(100~\text m,\) taking \(62.8~\text s\) for every circular lap. The average velocity and average speed for each circular lap, respectively, is:
| 1. | \(0,~0\) | 2. | \(0,\) \(10~\text{m/s},\) |
| 3. | \(10~\text{m/s},\) \(10~\text{m/s},\) | 4. | \(10~\text{m/s},\) \(0\) |
If three coordinates of a particle change according to the equations \(x = 3 t^{2}, y = 2 t , z= 4\), then the magnitude of the velocity of the particle at time \(t=1\) second will be:
1. \(2\sqrt{11}~\text{unit}\)
2. \(\sqrt{34}~\text{unit}\)
3. \(40~\text{unit}\)
4. \(2\sqrt{10}~\text{unit}\)
The coordinates of a moving particle at any time \(t\) are given by \(x= \alpha t^3\) and \(y = \beta t^3.\) The speed of the particle at a time \(t\) is given by:
| 1. | \(\sqrt{\alpha^{2} + \beta^{2}}\) | 2. | \(3t \sqrt{\alpha^{2} + \beta^{2}}\) |
| 3. | \(3t^{2} \sqrt{\alpha^{2} +\beta^{2}}\) | 4. | \(t^{2} \sqrt{\alpha^{2} +\beta^{2}}\) |
In \(1.0~\text{s}\), a particle goes from point \(A\) to point \(B\), moving in a semicircle of radius \(1.0~\text{m}\) (see figure). The magnitude of the average velocity is:
| 1. | \(3.14~\text{m/s}\) | 2. | \(2.0~\text{m/s}\) |
| 3. | \(1.0~\text{m/s}\) | 4. | zero |
A particle moves along the positive branch of the curve \(y= \frac{x^{2}}{2}\) where \(x= \frac{t^{2}}{2}\), & \(x\) and \(y\) are measured in metres and in seconds respectively. At \(t= 2~\text{s}\), the velocity of the particle will be:
| 1. | \(\left(\right. 2 \hat{i} - 4 \hat{j})~\text{m/s}\) | 2. | \(\left(\right. 4 \hat{i} + 2 \hat{j}\left.\right)\text{m/s}\) |
| 3. | \(\left(\right. 2 \hat{i} + 4 \hat{j}\left.\right) \text{m/s}\) | 4. | \(\left(\right. 4 \hat{i} - 2 \hat{j}\left.\right) \text{m/s}\) |
Two particles \(A\) and \(B,\) move with constant velocities \(\vec{v_1}\) and \(\vec{v_2}.\) At the initial moment their position vector are \(\vec {r_1}\) and \(\vec {r_2}\) respectively. The conditions for particles \(A\) and \(B\) for their collision to happen will be:
| 1. | \(\vec{r_{1 }} . \vec{v_{1}} = \vec{r_{2 }} . \vec{v_{2}}\) | 2. | \(\vec{r_{1}} \times\vec{v_{1}} = \vec{r_{2}} \times \vec {v_{2}}\) |
| 3. | \(\vec{r_{1}}-\vec{r_{2}}=\vec{v_{1}} - \vec{v_{2}}\) | 4. | \(\frac{\vec{r_{1}} - \vec{r_{2}}}{\left|\vec{r_{1}} - \vec{r_{2}}\right|} = \frac{\vec{v_{2}} - \vec{v_{1}}}{\left|\vec{v_{2}} - \vec{v_{1}}\right|}\) |
1. \(4~\text{m/s},\) \(53^\circ\) with \(x\)-axis
2. \(4~\text{m/s},\) \(37^\circ\) with \(x\)-axis
3. \(5~\text{m/s},\) \(53^\circ\) with \(y\)-axis
4. \(5~\text{m/s},\) \(53^\circ\) with \(x\)-axis
Two particles move from \(A\) to \(C\) and \(A\) to \(D\) on a circle of radius \(R\) and the diameter \(AB.\) If the time taken by both particles is the same, then the ratio of magnitudes of their average velocities is:
1. \(2\)
2. \(2\sqrt{3}\)
3. \(\sqrt{3}\)
4. \(\dfrac{\sqrt{3}}{2}\)
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