Although Newton`s laws of motion may seem obvious to us today, centuries ago they were considered revolutionary. The three laws of motion help us understand how objects behave when they stand still, when they move, and when forces act on them. This article describes Sir Newton`s three laws and a summary of their importance. Newton`s second law of motion describes what happens to the massive body when it is affected by an external force. The second law of motion states that the force acting on the body is equal to the product of its mass and acceleration. Newton`s third law of motion describes what happens to the body when it exerts force on another body. Question 2. Two people manage to push a car with a mass of 1200 kg at a constant speed on a flat road. The same car can be pushed by three people to produce an acceleration of 0.2ms-2.
How hard does each person push the car? (Let`s assume everyone pushes the car with the same muscular effort.) Answer: Each person must apply a force F to a motor vehicle with a mass in m = 1200 kg. When two people push the car, they simply manage to move it at a constant speed. This means that their combined 2F force is only compensated by the frictional force due to the movements of the road and the car at a uniform speed. When three people push the car, they exert a total force of 3F on the car. Now unbalanced force on the car = force exerted by three people – frictional force Sir Isaac Newton, natural philosopher and one of the world`s greatest scientists, listed the basics of force and the laws of motion in Newtonian mechanics. Physicists and astrophysicists have used these concepts with modern physics and explored the pristine parts of the universe. Given the importance of this subject in the modern world, students learn conceptual clarity regarding the concepts of force and laws of motion already at the school level. In India, it starts as early as the Grade 9 science program. Therefore, in this blog we have given an overview of the essential concepts that relate to force and the laws of motion.
NCERT Solutions Class 9 Science Chapter 9 Laws of Motion – Here are all NCERT solutions for Class 9 Science Chapter 9. This solution contains questions, answers, pictures, step-by-step explanations from the full Chapter 9 entitled Strength and Laws of Motion of Science, which was taught in Grade 9. If you are a grade 9 student using the NCERT textbook to study science, then you must come across Chapter 9 Laws of Force and Motion. After learning the lesson, you should look for answers to their questions. Get complete NCERT solutions for Class 9 Science Chapter 9 Force and Laws of Motion in one place. For a better understanding of this chapter, you should also read Chapter 9 Laws of Force and Movement Class 9 Notes, Science. Our mission is to provide free, world-class education to everyone, anywhere. Question 18 A negative sign indicates that the direction in which the gun would retaliate is opposite to that of the bullet. Two bodies, as shown in the figure, collide with each other and then connect. How fast will they move after the combination? Answer: Question 15. The diagram shows a moving truck. Forces A, B, C and D act on the truck.
Name the type of forces acting on a truck. Answer: Forces A, B, C and D acting on the truck are: Question 10. Why do athletes in an athletic race have a special posture with their right foot resting on a sturdy baby carrier? Answer: Athletes have to run the sleeves and they support their foot on a solid support before the start, so that during the start of the race, the athlete presses the support with a lot of force and this support gives him the same opposite push to start the race and get a good start to fight for the race. Question 10. Say Newton III`s law of motion. Answer: There is an equal and opposite reaction to each action, and they act on two different bodies. Question 1. Define strength.
Answer: It is a push or pull on an object that creates acceleration in the body on which it acts. 4 Question 16. An object with a mass of 100 kg is uniformly accelerated from a speed of 5 ms-1 to 8 ms-1 in 6 s. Calculate the initial and final pulses of the object. Also find the amplitude of the force exerted on the object. Answer: Question 1. Class V students played cricket in the cork room on the school grounds. Charu, an older student, told them about the accidents that can happen due to cork balls on campus and also advised them to bring a soft Cosco ball to play the game. a) Why was it safe to play with a softball and not with a hard cork ball? (b) A player pulls his hands backwards after firing the ball at high speed. What for? c) What is the value of Charu in this act? Answer: (a) The softball has less inertia than the heavy ball and would not harm the players.
(b) Pulling the hand backwards reduces the force that the bullet exerts on the hands. c) Charu showed the importance of being naturally responsible and helpful. To log in and use all Khan Academy functions, please enable JavaScript in your browser. Newton`s 3rd law states that for every action there is an equal and opposite reaction. The combined mass of the cyclist and the bicycle = 63 kg Muzzle velocity = 8.5 m/s Final speed = 0 m/s The stopping time of the bike = 3 s Question 15. An object with a mass of 1 kg, moving in a straight line at a speed of 10 ms-1, collides with a stationary block of wood with a mass of 5 kg and adheres to it. Then the two move together in the same straight line. Calculate the total pulse just before impact, just after impact and just after impact. Also calculate the speed of the combined object. Answer: The best content for viewing and it cleared up all my doubts. Personally, I think BYJU`S is the best app when it comes to online learning.
Thanks to Newton`s 2nd law of BYJU, the acceleration of an object, as generated by a net force, is directly proportional to the amplitude of the net force, in the same direction as the net force and inversely proportional to the mass of the object. Question 3. Explain why some leaves can break away from a tree when we vigorously shake its branch. Answer: When the branch of the tree is shaken vigorously, the branch begins to move, but the leaves remain at rest. Due to the slow rest, the leaves tend to stay in position and therefore detach from the tree to fall. Question 5 Why do outfield players gradually draw their hand with the ball moving while holding a hold? Answer: While catching a fast-moving cricket ball, an outfield player on the ground gradually pulls his hands back with the ball moving. This is done so that the outfield player increases to zero the time during which the high speed of the moving ball decreases. This reduces the acceleration of the ball and thus reduces the influence of fastball capture.
Question 2. State the 3 Newtonian laws of motion. Explain inertia and momentum. Answer: Newton`s law in I-motion: An object remains in a state of rest or uniform motion in a straight line, unless it is affected by an unbalanced external force. Newton`s Law of Motion II: The rate of change in the momentum of an object is proportional to the unbalanced force applied in the direction of the force. Law III of Newton`s motion: For every action, there is an equal and opposite reaction and they act on two different bodies. Inertia: The natural tendency of an object to resist a change in its resting state or uniform motion is called inertia. Momentum: The momentum of an object is the product of its mass and velocity and has the same direction as the velocity. Its S.I. unit is kgm/s.