(c) During time interval 3 to 6 s, the velocity of object is constant, so in this time interval, acceleration is zero and hence force, F (= ma) is zero.]. The second part says that a body in uniform motion continues to move in straight line path with a uniform speed, e.g., when a moving train stops suddenly a person sitting in it falls forward. (iii) Explain how a karate player can break a pile of tiles with a single blow of his hand. ⇒ v2 = —1.5 ms-1 Q5. Practice Now. We have Provided Force and Laws of Motion Class 9 Science MCQs Questions with Answers to help students understand the concept very well. State two effects, a force can produce in a non rigid body fixed at a position. What would be its momentum at the highest point of its reach? If so, in which direction? Extra Questions for Class 9 Science Chapter 9 Force and Laws of Motion. and the speed of gun, v2 = ? Answer: Name the physical quantity, which changes the shape of a ball. Q2. Justify your answer. Calculate (i) the resistive force exerted by the sand on the bullet. A bullet of mass 20 g is horizontally fired with a horizontal velocity 150 ms-1 from a pistol of mass 2 kg. Make a pile of similar carom coins on a table, as shown in figure. VERY SHORT ANSWER QUESTIONS. Attempt a sharp horizontal hit at the bottom of the pile using another carom coin or the striker. (c) Is there any time interval in which no force acts on the object? Question 1. State the meaning of recoil velocity of a gun? Total momentum of system after firing = Total momentum of system before firing Since the masses of the balls are not the same, therefore, the inertial forces are not same on both the balls. F1 > F2 or v2 = – 0.53 m/s. The mass of the cart is 3 kg. = 0.02 kg × 0 ms-1 + 2 kg × 0 ms-1 (a) Acceleration during interval 0 to 3 s Here you can get Class 9 Important Questions Science based on NCERT Text book for Class IX.Science Class 9 Important Questions are very helpful to score high marks in board exams. The force of friction exerted by the stone. A man throws a ball of mass 0.4 kg vertically upwards with a velocity of 10 m/s. Answer: Answer: That is, initial velocity of the ball, w = 30 ms-1 Short Answer Questions-I (SAQs-I) : 2 Marks. = 0.02 kg × 0 ms-1 + 2kg × 0 ms-1 What type of force is acting in the cases given above ? For pistol: m2 = 2kg, u2 = 0 ms-1, It might overwhelm you with its language but I feel if you can understand the content is authentic with plenty of problems to solve. Q1. Question 11. Here, the mass of the bullet, m1 = 0.02 kg Q3. What are the effects of the following on inertia of a body? Q4. (b) Calculate the force on the object in the time interval 6 to 10 s. Write its S.I. Force is push or pull acting upon any object or body. 3 + 2v2 = 0 We can increase the velocity of our bicycle by pedaling harder, i.e., on applying more force. A force of 2N acting on a body changes its velocity uniformly from 2 m/s to 5m/s in 10s. Here -ve sign indicates that the force is retarding or stopping force. Time, t = 6 s [NCERT Exemplar] ⇒ 2v2 = – 3 unit. or, 0.02 × 200 + 7.5 × v2 = 0 Name the force which is responsible for change in position or state of an object. Q5. Check the below NCERT MCQ Questions for Class 9 Science Chapter 9 Force and Laws of Motion with Answers Pdf free download. When we kick a football, it flies a long way but at the same time if we kick a stone of the same size, it hardly moves, as the stone resists a change in its motion better than the football because of its more mass. or, v = $$\frac{200}{43}$$ = 4.65 ms-1 Question 10. NCERT Solutions of Chapter 9 Force and Laws of Motion, Notes of Chapter 9 Force and Laws of Motion, CBSE Previous Year Question Paper for Class 10, CBSE Previous Year Question Paper for Class 12. Name the unbalanced force which slows down a moving bicycle when we stop pedaling it. According to the law of conservation of momentum, This is because as the train stops, the lower part of the person’s body comes to rest along with the bus while upper part of his body continues to remain in ^notion due to inertia of motion and thus he falls forward. Q2. = 43v kg ms-1 Thus, the boy on cart would move with a velocity of 4.65 ms-1 in the direction in which the boy jumped onto the cart. Also, the total momenta after the interaction On reaching the ground, the iron sphere comes to rest, so its final momentum is equal to zero according to the law of conservation of momentum. Force and Laws of Motion Class 9 Important Questions and Answers Science Chapter 9. According to the law of conservation of momentum, we have Q2. i.e., m1v1 + m2v2 = 0 Q2. Negative sign indicates that the direction in which the pistol would recoil is opposite to that of bullet (right to left). Extra Questions for Class 9th: Ch 9 Force and Laws of Motion (Science) Important Questions Answer Included Very Short Answer Questions (VSAQs): 1 Mark Q1. Q.1 Define the force . Q4. This set of questions contains all the possible concepts which could be asked in the examination. One boy dropped his sheet of paper as such, while the other boy dropped it by changing it in the shape of a ball. Total momenta of the pistol and bullet before the fire Answer The velocity with which a gun moves backward after firing a bullet is called the recoil velocity of a gun. MCQ Questions for Class 9 Science with Answers were prepared based on the latest exam pattern. FORCE AND LAWS OF MOTION. = (3+ 2v2) kg ms-1 Multiple Choice Questions (ii) the time taken by the bullet to come to rest, Answer: No, it implies that all the forces acting on the body are balanced. It can deform a body, i.e., it can change its shape. = 0 kg ms-1 = 40 kg × 5 ms-1 + 3 kg × 0 ms-1 Negative sign shows that the ball is retarded or decelerated. (ii) How much momentum will an object of mass 10 kg transfer to the floor, if it falls from a height of 5 m (g =10 m/s. According to law of conservation of momentum, we have Total momenta of the pistol and bullet after the fire That is, when F = 0, v = u for whatever time, t is taken. 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