## 1. Newton's first law of motion is also known as:

### Answer:

### Explanation:

Newton's first law, which states that an object remains at rest or in uniform motion unless acted upon by an external force, is often termed the Law of Inertia.

## 2. If the net external force on an object is zero, its momentum:

### Answer:

### Explanation:

According to Newton's first law, if no net force acts on an object, its velocity remains constant, and so does its momentum.

## 3. The rate of change of momentum is directly proportional to:

### Answer:

### Explanation:

Newton's second law states that the rate of change of momentum of an object is directly proportional to the force applied and occurs in the direction of the force.

## 4. An object of mass m moving with velocity v has a momentum p. If the velocity is doubled, the momentum becomes:

### Answer:

### Explanation:

Momentum is the product of mass and velocity. Doubling the velocity doubles the momentum.

## 5. Action and reaction forces:

### Answer:

### Explanation:

According to Newton's third law, for every action, there is an equal and opposite reaction. These forces act on different bodies.

## 6. The measure of inertia is:

### Answer:

### Explanation:

The natural tendency of an object to resist changes in its state of motion is termed inertia. This resistance is directly proportional to the object's mass.

## 7. If a car takes a sharp turn, the passengers inside tend to move towards the outer edge because of:

### Answer:

### Explanation:

When a car turns, the passengers experience an outward force due to their inertia, often termed as centrifugal force in a rotating reference frame.

## 8. A book kept on a table is an example of:

### Answer:

### Explanation:

The book exerts a downward force (action) due to gravity, while the table provides an upward force (reaction) in accordance to Newton's third law.

## 9. The product of force and time for which it acts on a body is called:

### Answer:

### Explanation:

Impulse is the product of force and the time interval during which it acts and results in a change in momentum.

## 10. A force of 5N acts on a body for 2 seconds. The impulse imparted to the body is:

### Answer:

### Explanation:

Impulse = Force x Time = 5N x 2s = 10 Ns.

## 11. When a body moves in a circular path, it constantly changes its:

### Answer:

### Explanation:

Even if the body moves with a constant speed, its direction changes, and hence, velocity changes.

## 12. The frictional force acts:

### Answer:

### Explanation:

Frictional force always opposes the relative motion or tendency of such motion between two surfaces in contact.

## 13. A car moving with a velocity v is stopped by applying brakes. The distance covered by the car during this process is directly proportional to:

### Answer:

### Explanation:

Stopping distance or skid distance s = v^2/2gμ, where μ is the coefficient of friction. Thus, it's directly proportional to v^2.

## 14. A force F acts on a body of mass m and produces an acceleration a. The same force acts on another body of mass 2m, the acceleration produced is:

### Answer:

### Explanation:

According to Newton's second law, F = ma. When the force is constant, acceleration is inversely proportional to mass.

## 15. The weight of an object on the moon is:

### Answer:

### Explanation:

The gravitational acceleration on the moon is about 1/6th of that on Earth, so the weight (which is proportional to gravitational acceleration) is 1/6th.