A car of mass \(m\) is moving on a level circular track of radius \(R\). If \(\mu_s\) represent the static friction between the road and tyres of the car, then the maximum speed of the car in circular motion is given by:

1.	\(\sqrt{\mu_{s} mRg} \)	2.	\(\sqrt{Rg / \mu_{s}}\)
3.	\(\sqrt{mRg / \mu_{s}} \)	4.	\(\sqrt{\mu_{s} {Rg}}\)

A person of mass 60 kg is inside a lift of mass 940 kg and presses the button on control panel. The lift starts moving upwards with an acceleration $1.0$ $\mathrm{m}/{\mathrm{s}}^2$. If $\mathrm{g}=10$ $\mathrm{m}/{\mathrm{s}}^2$, the tension in the supporting cable is:

1. 9680 N

2. 11000 N

3. 1200 N

4. 8600 N

Two masses of 10 kg and 20 kg respectively are connected by massless spring as shown in the figure. A force of 200 N acts on the 20 kg mass. At the instant shown the 10 kg mass has acceleration 12 $\mathrm{m}/{\mathrm{s}}^2$. What is the acceleration of 20 kg mass?

1. 12 $\mathrm{m}/{\mathrm{s}}^2$

2. 4 $\mathrm{m}/{\mathrm{s}}^2$

3. 10 $\mathrm{m}/{\mathrm{s}}^2$

4. zero

The slope of a smooth banked horizontal surface road is $p$. If the radius of the curve be $r$, the maximum velocity with which a car can negotiate the curve is given by

(a) $prg$

(b) $\sqrt{prg}$

(c) $p\mathit{/}rg$

(d) $\sqrt{p\mathit{/}rg}$

The angle of banking at the turning of a road does not depend upon the

(a) Mass of vehicle

(b) Acceleration due to gravity

(c) The velocity of the vehicle

(d) Radius of the curved path

A block of mass m is in contact with the cart C as shown in the figure.

The coefficient of static friction between the block and the cart is $\mu .$The acceleration $\alpha$ of the cart that will prevent the block from falling satisfies

1. $\alpha >\frac{mg}{\mu }$                                       2. $\alpha >\frac{g}{\mu m}$

3. $\alpha \ge \frac{g}{\mu }$                                          4. $\alpha <\frac{g}{\mu }$

A gramophone record is revolving with an angular velocity $\omega .$ A coin is placed at a distance r from the centre of the record. The static coefficient of friction is $\mu .$ The coin will revolve with the record if: 

1. $r=\mu g{\omega }^2$                                       2. $r<\frac{{\omega }^2}{\mu g}$

3. $r\le \frac{\mu g}{{\omega }^2}$                                         4. $r\ge \frac{\mu g}{{\omega }^2}$

The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, its acceleration is:

1. $30 {\mathrm{ms}}^{-2} \mathrm{downwards}$                                     
2. $4 {\mathrm{ms}}^{-2} \mathrm{upwards}$
3. $4 {\mathrm{ms}}^{-2} \mathrm{downwards}$                                       
4. $14 {\mathrm{ms}}^{-2} \mathrm{upwards}$

A body, under the action of a force $\overrightarrow{F}=6\hat{i}-8\hat{j}+10\hat{k},$ acquires an acceleration of 1$m{s}^{-2}.$ The mass of this body must be

(1) $20\sqrt{10}kg$                                   

(2) 10kg

(3) 20kg                                         

(4) $10\sqrt{2}kg$                                

Three forces acting on a body are shown in the figure. To have the resultant force only along the y-direction, the magnitude of the minimum additional force needed is 

1. 0.5N

2. 1.5N

3. $\frac{\sqrt{3}}{4}$ N

4. $\sqrt{3}$N