recoil velocity of the pistol? NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. It is developed keeping in mind the concept-based approach, along with the precise answering method for examinations. Answer: Question 2. Therefore, the leaves that are weakly attached to the branch fall off due to inertia whereas the leaves that are firmly attached to the branch remain attached. 4. Thus, from Newton’s third law of motion, an equal amount of force will act in the opposite direction. (c) a five-rupee coin and a one-rupee coin? What is law of conservation of momentum? For an athletic races why do athletes have a special posture with their right foot resting on a solid supporter? Fielder giving a swing while catching a ball is an example of Give 3 examples in daily life which shows inertia. What is S.I. unit of force? That means the body will remain under accelerated motion for 0.1 sec. Solution of problem 1. The acceleration of the ball is decreased and therefore the impact of catching the fast moving ball4s reduced. NCERT Class 9 Science Chapter 9 Force and laws of motion, also describes the natural tendency of objects to resist a change in their state of rest or of uniform motion known as inertia in a detailed way. Answer: Question 16. (a) the earths gravitational force acts on it Stuck At Home? The NCERT Solutions to the questions after every unit of NCERT textbooks aimed at helping students solving difficult questions.. For a better understanding of this … Negative sign indicates that the direction in which the pistol would recoil is opposite to that of bullet. (c) no unbalanced force acts on it To change the state of motion, a net non-zero external unbalanced force must be applied on the object. NCERT Solutions for Class 9 science is designed and developed by the subject experts and teaching faculty having experience in coaching students. Answer: It is a push or pull on an object that produces acceleration in the body on which it acts. Question 14. Terminal velocity (v) = 0 m/s (the stone reaches a position of rest), Distance traveled by the stone (s) = 50 m, 7. Answer: The water that is ejected out from the hose in the forward direction comes out with a large momentum and equal amount of momentum is developed in the hose in the opposite direction and hence the hose is pushed backward. “A football player kicks a football to another player of his team who kicks the football towards the goal The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team”. But when driver applies sudden breaks or stops the car our body tends to continue in the same state of motion because of its inertia. (a) It can change the speed of a body. calculate the force required to keep the gun in position. A force of 200 N is applied in the forward direction. In an isolated system, the total momentum remain conserved. Answer: While we are travelling in a moving car, our body remains in the state of rest with respect to the seat. Question 8. unit of force is Newton. This is why the dust comes out of the carpet when beaten. An object experiences a net zero external unbalanced force. An automobile vehicle has a mass of 1500 kg. Answer: This is because stone is heavier than football and heavier objects offer larger inertia. The acceleration of the train is 1.94 m.s-2. Since the mass of the car is very high, the force exerted on the insect during the collision is also very high. Answer: An object remains in a state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? 9. And Newton’s third law explains how these forces acting on a body are interrelated. As per the law of conservation of momentum, the total momentum before the collision between the insect and the car is equal to the total momentum after the collision. The velocity of football changed four times. Answer: What is inertia? 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. Answer 2: When we push a massive truck parked along the roadside, it does not move. Question 4. A bullet of m.ass 20 g is horizontally fired with a velocity 150 m/s from a pistol of mass 2 kg. The following is the distance-time table on an object in motion: Provides completely solved solutions to all the questions present in the chapter. In cricket field, the fielder gradually pulls his hands backward while catching a ball. NCERT Solutions Class 9 Science Chapter 9 Force And Laws Of Motion. Take its downward acceleration to be 10 ms–2. Then, there is no net unbalanced force applied on the body. किसी पेड़ की शाखा को तीव्रता से हिलाने पर कुछ पत्तियाँ झड़ जाती हैं। क्यों? A machine gun fires 25 g bullets at the rate of 600 bullets per minute with a speed of 200 m/s. Define one Newton. Answer: The rate of change of momentum of an object is proportional to the applied unbalanced force in the direction of force. (b) To every action there is an equal and opposite reaction, both act on different bodies. From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m/s. (p = mv). जब कोई गतिशील बस अचानक रूकती है तो आप आगे की ओर झुक जाते हैं और जब विरामावस्था से गतिशील होती है तो पीछे की ओर हो जाते हैं, क्यों? To avoid the fall of the luggage, it is tied with the rope. Also, calculate the velocity of the combined object. With what velocity would the two move together? Therefore, this sudden break may cause injury to us by impact or collision. A body of mass 1 kg is kept at rest. Therefore, the acceleration of the object is increasing. Answer: A body of mass 20 kg will have more inertia. The justification given by the student that the two forces and equal forces cancel each other is totally wrong. A batsman hits a cricket ball which then rolls on a level ground. Answer. What Policies Can Help Students Affected by COVID-19? If the collision lasts for 1 s: Answer 3: 10 n ; 13 m/s, Copyright 2020 by Tiwari Academy – A step towards Free Education. (a) The soft ball will have less inertia as compared to the heavy ball and it would not hurt the players. (c) act in same direction (d) both (a) and (c) Question 4. Question 10. NCERT Solutions for Class 9 explains motion and causes of motion in a detailed way. (a) The distance covered by the object at any time interval is greater than any of the distances covered in previous time intervals. State Newton’s III law of motion. Calculate the force exerted by the brakes on the motorcar if the mass along with the passengers is 1000 kg. How are safety belts helpful in preventing any accidents?