NCERT Solutions for Class 9 Science Chapter 9 Force and Laws of Motion

### A:

As per the conservation of momentum,

(momentum of motorcar + momentum of insect)before

= (momentum of motorcar + momentum of insect)after

∴ Change in in momentum = 0

The direction of the insect gets reversed when it stuck on the windscreen and the velocity of the insect changes to a great extend. The motorcar continues moving with a constant velocity in the forward direction.

As, Kiran suggested that the insect suffers a greater change in momentum as compared to the motorcar hence, it is correct. The momentum of the insect after collision becomes very high as the motorcar is moving at a very high speed. Therefore, the momentum gained by the insect is equal to the momentum lost by the motorcar.

Secondly, Akhtar is also correct as the mass of the motorcar is very large as compared to the mass of the insect and the speed of the motorcar is also very high.

Now, Rahul’s explanation is correct as both the car and the insect experienced equal forces caused by the Newton’s action-reaction law. But Rahul’s statement becomes incorrect when he said that the system suffers a change in momentum because the momentum before the collision is equal to the momentum after the collision.

### A:

The static friction acting between the truck and the road is very large as the truck is very massive. Thus, truck does not move when someone pushes it. Therefore, it can be concluded that the applied force in one direction is cancelled out by the frictional force of equal amount acting in the opposite direction.

### A:

When the force of 200 N is applied on wooden cabinet, an equal and opposite force acts on it. This opposite force is the frictional force. Therefore, a frictional force of 200 N is exerted on the cabinet.

### A:

The correct option is (c)

Explanation: Here, the ball comes to rest due to frictional force which opposes its motion. Frictional force always acts in the direction opposite to the direction of motion. Therefore, this force tries to stop the ball.

### A:

Yes. It is possible that an object is moving with a non-zero velocity even when the object experiences a net zero external unbalanced force. It is possible only when the object has been moving with a constant velocity in a certain direction. In order to change the state of motion, a net non-zero external unbalanced force must be applied on the object.

### A:

When the bus starts accelerating in forward direction, it comes in the state of motion but the luggage kept on the roof remains in the state of rest. Therefore, with the forward movement of the bus, the luggage remains at its original position and finally falls from the roof of the bus. Hence, it is advised to tie any luggage kept on the roof of a bus.

### A:

Due to inertia, an object opposes any change in its state of rest or state of motion. As soon as the carpet is beaten with a stick, the carpet comes into motion while the dust particles oppose their state of rest. As per Newton’s first law of motion, the dust particles remain stationary, while the carpet moves. Therefore, the dust particles come out of the carpet.

### Benefits of NCERT Solutions

Following are some of the benefits of using NCERT Solutions by Extramarks.

1. They are developed by our experts with the right approach for precisely answering the textbook questions.

2. They are free of cost and available online to help class 9 students.

3. They not only explain every topic but also prepare students for further examinations.

4. They are proven to be helpful to students in their exam preparation, homework and competitive exams.

5. They will help in understanding the solutions and the methodology of writing the answers in the exams.

### Tips & Strategies for Class 9 Exam Preparation

1. Jot down important chapters or topics for your exam preparation.

2. Learn from the best teachers with Extramarks and clear your doubts instantly.

3. While practicing, refer to NCERT Solutions for class 9 to understand step-by-step solutions to all questions.

4. Solve as many sample papers as you can to prepare well for the exams.

5. Lastly, don’t panic. Try to meditate at least for 15 minutes every day- it will help you retain things better.

### Why opt for Extramarks NCERT Solutions for Class 9 ?

Extramarks provide NCERT Solutions for all subjects at your fingertips. These solutions are designed by subject matter experts and provide solutions to every NCERT textbook questions. These solutions help students in their exam preparation and home assignments. We hope NCERT Solutions for class 9 will come in handy for every student and help them understand everything in a better way.

When to refer to NCERT Solutions for Class 9?

You can refer to NCERT solutions for class 9 anytime during your academic year. Whether you are preparing for class tests or unit tests or pre-board exams, you can refer to the class 9 NCERT solutions easily. The NCERT solutions are available on Extramarks - The Learning App and Extramarks website in the footer section.

What can I do to get better marks in Class 9?

If you want to gain good marks in Class 9 examination then we suggest that you go through NCERT books solutions for class 9 listed on the Extramarks website. The solutions are self-explanatory and written in easy to understand language so you can easily learn and ace your exams with the help of these solutions.

Why are the NCERT solutions Important for Class 9?

NCERT solutions class 9 are self-explanatory and form the basis of examination. Since the exam syllabus is taken directly out of the NCERT books, studying NCERT solutions becomes important to prepare for the exams.

What are some expert tips to score good marks in Class 9 CBSE?

If you want to score good marks in Class 9, follow these tips:

1. Study NCERT Solutions from Extramarks website.

2. Study using Extramarks - The Learning App, practice using the sample papers, and prepare through the interactive video modules.

3. Prepare a timetable and schedule your subjects and save time for revision.. Get concept clarity by tuning in to the Extramarks live classes.

How to Prepare for Competitive Exam Through NCERT Class 9 Solutions?

NCERT solutions for Class 9 science are amazingly useful for JEE and NEET and if you are preparing for any other competitive exam then consider studying through the NCERT solutions listed on the Extramarks website. You can also study the 9-10 and other classes syllabus on Extramarks - The Learning App.

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