Q. No.A wheel has an angular acceleration of 3.0 rad/s2 and an initial angular speed of 2.00 rad/s. In a time of 2 s,
it has rotated through an angle (in radian) of:
1. 6
2. 10
3. 12
4. 4
An electric fan rotating at 1200 rpm is switched off. If the fan stops after 10 seconds, the number of revolutions completed by the fan before it stops will be: (assume uniform retardation)
| 1. | 100 | 2. | 50 |
| 3. | 40 | 4. | 20 |
For a body, with angular velocity \( \vec{\omega }=\hat{i}-2\hat{j}+3\hat{k}\) and radius vector \( \vec{r }=\hat{i}+\hat{j}++\hat{k},\) its velocity will be:
1. \(-5\hat{i}+2\hat{j}+3\hat{k}\)
2. \(-5\hat{i}+2\hat{j}-3\hat{k}\)
3. \(-5\hat{i}-2\hat{j}+3\hat{k}\)
4. \(-5\hat{i}-2\hat{j}-3\hat{k}\)
For a rigid body rotating about a fixed axis, which of the following quantities is the same at an instant for all the particles of the body?
| 1. | Angular acceleration |
| 2. | Angular velocity |
| 3. | Angular displacement in the given time interval |
| 4. | All of these |
If a body is moving in a circular path with decreasing speed, then: (symbols have their usual meanings):
1.
2.
3.
4. All of these
Two gear wheels that are meshed together have radii of 0.50 cm and 0.15 cm. The number of revolutions made by the smaller one when the larger one goes through 3 revolutions is:
1. 5 revolutions
2. 20 revolutions
3. 1 revolution
4. 10 revolutions
Particles A and B are separated by 10 m, as shown in the figure. If A is at rest and B started moving with a speed of 20 m/s then the angular velocity of B with respect to A at that instant is:
| 1. | 1 rad s-1 | 2. | 1.5 rad s-1 |
| 3. | 2 rad s-1 | 4. | 2.5 rad s-1 |
A rigid body rotates about a fixed axis with a variable angular velocity equal to \(\alpha\) \(-\) \(\beta t\), at the time t, where \(\alpha , \beta\) are constants. The angle through which it rotates before it stops is:
| 1. | \(\frac{\left(\alpha\right)^{2}}{2 \beta}\) | 2. | \(\frac{\left(\alpha\right)^{2} - \left(\beta\right)^{2}}{2 \alpha}\) |
| 3. | \(\frac{\left(\alpha\right)^{2} - \left(\beta\right)^{2}}{2 \beta}\) | 4. | \(\frac{\left(\alpha-\beta\right) \alpha}{2}\) |
The angular speed of the wheel of a vehicle is increased from \(360~\text{rpm}\) to \(1200~\text{rpm}\) in \(14\) seconds. Its angular acceleration will be:
| 1. | \(2\pi ~\text{rad/s}^2\) | 2. | \(28\pi ~\text{rad/s}^2\) |
| 3. | \(120\pi ~\text{rad/s}^2\) | 4. | \(1 ~\text{rad/s}^2\) |
A wheel is subjected to uniform angular acceleration about its axis. Initially, its angular velocity is zero. In the first 2 sec, it rotates through an angle θ1. In the next 2 seconds, it rotates through an additional angle θ2. The ratio of θ2/θ1 is:
| 1. | 1 | 2. | 2 |
| 3. | 3 | 4. | 5 |
© 2024 GoodEd Technologies Pvt. Ltd.