force and laws of motion class 9 questions with answers
Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m/s and 1 m/s respectively. Explain why some of the leaves may get detached from a tree if we vigorously shake its branch. Newton: A force of one Newton produces an acceleration of 1 m/s2 on an object of mass 1 kg. Calculate the initial recoil velocity of the rifle. What change will force bring in a body? Answer: A vehicle moving on mountains is in the inertia of motion. Question 13. Question 7. The S.I. Types of forces: (i) Balanced force: When the forces acting on a body from the opposite direction do not change the state of rest or of motion of an object, such forces are called balanced forces. Answer: Momentum of two bodies before collision is equal to the momentum after collision.In an isolated system, the total momentum remain conserved. State Newton’s first law of motion. -ve sign of acceleration, charge in momentum and force suggests that the force is opposing the motion of motor car. (a) Why it was safe to play with soft ball and not with hard cork ball? A truck starts from rest and rolls down a hill with a constant acceleration. NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. When he suddenly touches the ground he comes to rest in a very short time and hence the force exerted by the hard concrete surface on his body is very high, and the person gets hurt. Answer: Question 14. Is it possible for the object to be travelling with a non-zero velocity? 5. The two bodies collide and force is exerted by each body. Question 4. Answer: Question 8. Calculate the total momentum just before the impact and just after the before the impact and just after the impact. From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m/s. A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. This is explained with the help of suitable examples and demonstrations. Answer: In a high jump athletic event, athletes are made to fall either on a cushioned bed or on a sand bed so as to increase the time of the athlete’s fall to stop after making the jump. Solution 1. Total momentum of two bodies before collision= m1u1 +m2u2= 60 × 5 + 55 × -6= -30 kg m/s, If v is the velocity of two joined bodies. Akhtar and Kiran started pondering over the situation. The product of mass and velocity gives a physical quantity Initial momentum before collision = Final momentum after collision The first section of the chapter deals with balanced and unbalanced forces. 9. (c) the product ‘mi/ is same for both bodies recoil velocity of the pistol? In the following example, try to identify the number of times the velocity of ball changes: “A football … (c) Newton’s II law of motion (d) Newton’s I law of motion Question 10. And Newton’s third law explains how these forces acting on a body are interrelated. They collide and after the collision the first object moves at a velocity of 1.67 m./s. When 2 bodies collide: 14: What decides the rate of change of momentum of an object?Answer: The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of force. Answer: To every action, there is an equal and opposite reaction and they act on two different bodies. We slip to one side of the seat due to the inertia of our body. If yes, state the conditions that must be placed on the magnitude and direction of the velocity. 1. The following is the distance-time table on an object in motion: Question 6. Answer: While moving in a bus our body is in motion. When two persons push the car, they just manage to move it at a uniform velocity. Inertia: The natural tendency of an object to resist change in their state of rest or of motion is called inertia. Why are roads on mountains inclined inwards at turns? If action is always equal to the reaction, explain how a horse can pud a cart? Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect. In an isolated system, the total momentum remain conserved. (c) Newton ( (d) Newton-meter The same motorcar can be pushed by three persons to produce an acceleration of 0.2 ms-2. When a carpet is beaten with a stick, dust comes out of it. What is Motion? When we are travelling in a vehicle and sudden brakes are .applied we tend to fall forward. Question 8. (c) It can change the shape of the body.The S.I. 1: Define force.Answer: It is a push or pull on an object that produces acceleration in the body on which it acts. Question 5. Calculate the change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick. _____ (Nuclear/Gravitational/Muscular) Force is the weakest force 9. If the object was initially in a state of motion, then in accordance with the first law of motion, the object will continue to move in same direction with same speed. If you have any query regarding NCERT Solutions for Class 9 Science Chapter 9 Force and Laws of Motion, drop a comment below and we will get back to you at the earliest. Class V students were playing cricket with the cork hall in the school campus. Class 9 Science Force and Laws of Motion Chapter 9 Class 9 Science Explanation in Hindi, Imp Questions and Answers. What decides the rate of change of momentum of an object? Answer: Newton’s 1st law of motion: An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force. Types of inertia:Inertia of rest: The object at rest will continue to remain at rest unless acted upon by an external unbalanced force. 1: The product of mass and velocity of a body is called __________. When we kick a football its mass is less and inertia is also less so force applied by our kick acts on it and hence it shows larger displacement but in case of stone, it has larger mass and offers larger inertia. But when an unbalanced force is applied by the engine to change the direction of motion of the motorcar. (b) Frictional force exerted on the body is more than 50 N m1 u1+ m2 u2 = m1 v1+ m2 v2 2: What is S.I. In this case the horse exerts a force on the ground with its feet while walking, the ground exerts an equal and opposite force on the feet of the horse, which enables the horse to move forward and the cart is pulled by the horse. Question 1. If the collision lasts for 1 s: If we want to remove the dust from carpet we beat the carpet so that dust fall down. (a) a rubber ball and a stone of the same size? When we are travelling in a vehicle and sudden brakes are .applied we tend to fall forward.2. Question 9. (c) there is a force on the ball opposing the motion. When three persons push the car, they apply a total force 3F on the car. Download free PDF of best NCERT Solutions , Class 9, Physics, CBSE-Forces and Laws of Motion . (a) How can a karate expert break the slate without any injury to his hand? The small force exerted on the truck cannot move it and the truck remains at rest. Answer: According to second law, F = ma If F = 0, a =0 since m ≠ 0, But a = \(\frac{v-u}{t}\) or, v – u =0 so, v = u for whatever time t is taken. unit is kg. (a) It can change the speed of a body. Ncert solutions for class 7 Now net unbalanced force’ on the car = force applied by three persons – frictional force. Access Answers of Science NCERT class 9 Chapter 9: Force and Laws Of Motion(All intext and exercise questions solved) Intext Questions – 1 Page: 118. unit of force? Saksham saw his karate expert friend breaking a slate. Answer: The carpet with dust is in state of rest. Answer: When forces acting on a body from the opposite direction do not change the state of rest or of motion of an object, such forces are called balanced forces. Answer: Question 16. Also calculate the magnitude of the force exerted by the wooden block on the bullet. Action and reaction forces Answer: This is because stone is heavier than football and heavier objects offer larger inertia.When we kick a football its mass is less and inertia is also less so force applied by our kick acts on it and hence it shows larger displacement but in case of stone, it has larger mass and offers larger inertia. 2. On moving/turning around the tray at faster speed the water spills because the tray and the tumbler comes into motion while the water in the tumbler remain at inertia of rest. Physics-Force & Laws of Motion: Questions 1-6 of 41. (a) A karate player applies the blow with large velocity in a very short interval of time on the slate, therefore large force is exerted on the slate and it breaks. Inertia of motion: The object in the state of uniform motion will continue to remain in motion with same speed and direction unless it is acted upon by an external unbalanced force. (p = mv). Question 13. A push or pull on an object that may or may not change its position is referred to as force. In CBSE Class 9 Science Chapter 9 – Force and Laws of Motion, students will study topics related to the laws of motion, inertia and mass, momentum, etc. Answer: In moving vehicle like bus, the motion is not uniform, the speed of vehicle varies and it may apply brake suddenly or takes sudden turn. 12: Name the factor on which the inertia of the body depends.Answer: Inertia of a body depends upon the mass of the body. p = m x v. Question 3. . The CBSE Class 9 Science notes on chapter 9 ‘Force and Laws of Motion’ are available in this article. Answer: Force: It is a push or pull on an object that produces acceleration in the body on which it acts. Ncert solutions for class 12 . When it is beaten with a stick the carpet is set in motion, but the dust particles remain at rest. RD Sharma solutions for class 11 Newton’s I law of motion: An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force. Explain different types of inertia. Answer: Rahul gave the correct reasoning and explanation that both the motorcar and the insect experienced the same force and a change in their momentum. The rate of change of momentum of an object is proportional to Answer: The forces A, B, C and D acting on the truck are:A → driving forceB → reacting forceC → frictional forceD → weight/gravitational force. Why are roads on mountains inclined inwards at turns? The document Short & Long Answer Questions (part- 1)- Force and Laws of Motion Class 9 Notes | EduRev is a part of the Class 9 Course Science Class 9 . 11:Why do you think it is necessary to fasten your seat belts while travelling in your vehicle?OrHow are safety belts helpful in preventing any accidents? Explain different types of inertia. Topics and Sub Topics in Class 9 Science Chapter 9 Force and Laws of Motion: These solutions are part of NCERT Solutions for Class 9 Science. 1 N = 1 kg m/s2. Comment on these suggestions. Answer: While catching a. fast moving cricket ball, a fielder on the ground gradually pulls his hands backwards with the moving ball. This will help you make preparations for your exams in an effective manner. For a better understanding of this chapter, you should also see Chapter 9 Force and Laws of Motion Class 9 notes , Science. (a) both have same inertia (b) both have same momentum