Two blocks \(A\) and \(B\) of masses \(4\ \text{kg}\) and \(12\ \text{kg}\) are placed on a smooth plane surface. A force \(F\) of \(16\ \text{N}\) is applied on A as shown. The force of contact is:

 

1. \(4\ \text{N}\)

2. \(8\ \text{N}\)

3. \(12\ \text{N}\)

4. \(16\ \text{N}\)

The engine of a car produces an acceleration of 4 m/s² in the car. If this car pulls another car of the same mass, what will be the acceleration produced?

1. 8 m/s²

2. 2 m/s²

3. 4 m/s²

4. $\frac{1}{2}m/s^2$   

A truck and a car are moving with equal velocity. If equal retarding force is applied on each, then on applying the brakes both will stop after certain distance 

1. Truck will cover less distance before rest

2. Car will cover less distance before rest

3. Both will cover equal distance

4. None

A constant force acts on a body of mass \(0.9\ \text{kg}\) at rest for \(10\ \text{s}\). If the body moves a distance of \(250\ \text{m}\), the magnitude of the force is:

1. \(3\ \text{N}\)

2. \(3.5\ \text{N}\)

3. \(4.0\ \text{N}\)

4. \(4.5\ \text{N}\)

Two particles of equal mass are revolving in circular paths of radii \(r_1\) and \(r_2\) respectively, with the same speed. The ratio of their centripetal forces is:

1. \(\dfrac{r_2}{r_1}\)

2. \(\sqrt{\dfrac{r_2}{r_1}}\)

3. \(\dfrac{r_1^2}{r_2}\)

4. \(\dfrac{r_2^2}{r_1}\)

If the overbridge is concave instead of being convex, the thrust on the road at the lowest position will be:
1. \(mg+\dfrac{mv^2}{r}\)
2. \(mg-\dfrac{mv^2}{r}\)
3. \(\dfrac{mv^2g}{r}\)
4. \(\dfrac{v^2g}{r}\)

A particle moves in a circular orbit under the action of a central attractive force inversely proportional to the distance \(r\). The speed of the particle is:

1. Proportional to \(r^2\)

2. Independent of \(r\)

3. Proportional to \(r\)

4. Proportional to \(\dfrac 1r\)

A \(500\ \text{kg}\) car takes a round turn of radius \(50\ \text{m}\) with a velocity of \(36\ \text{km/h}\). The centripetal force is:

1. \(250\ \text{N}\)

2. \(750\ \text{N}\)

3. \(1000\ \text{N}\)

4. \(1200\ \text{N}\)

A stone of mass \(16\ \text{kg}\) is attached to a string \(144\ \text{m}\) long and is whirled in a horizontal circle. The maximum tension the string can withstand is \(16\ \text{N}\). The maximum velocity of revolution that can be given to the stone without breaking it will be:

1. \(20\ \text{ms}^{–1}\)
2. \(16\ \text{ms}^{–1}\)
3. \(14\ \text{ms}^{–1}\)
4. \(12\ \text{ms}^{–1}\)

A point mass \(m\) is suspended from a light thread of length \(l,\) fixed at \(O\), and is whirled in a horizontal circle at a constant speed as shown. From your point of view, stationary with respect to the mass, the forces on the mass are:

1.		2.
3.		4.