(ii) B to C and Can the displacement be greater than the distance travelled by an object? (i) Final velocity = v = 2u = 2 à 5 à 104ms-1 = 10 à 104ms-1 Question 4. Initial difference in height = (150 – 100) m = 50 m same direction. The phenomenon of motion was placed on a sound scientific footing by two scientists. Distance travelled by another body in 2 s = h2 = 0 + \(\frac{1}{2}\) g(2)2 = 2g We have, BE = 6m/s, EC = 16 – 10 = 6s (i) A to B Can a body have constant speed but variable velocity? For a uniformly accelerated motion, velocity-time graph is always a straight line. An object starting from rest travels 20 m in first 2s and 160 m in next 4s. (i) Part AB Thus, the effect of force of friction has to be balanced. Answer: The adjoining figure shows the displacement-time graph for a body moving with uniform velocity. A cheetah is the fastest land animal and can achieve a peak velocity of 100 km/h up to distances less than 500 m. If a cheetah spots its prey at a distance of 100 m, what is the minimum time it will take to get its prey, if the average velocity attained by it is 90 km/h? Plot a velocity-time graph for the same. (v) Speed between 10:40 AM to 11:00 AM = \(\frac{\text { Distance }}{\text { Time }}=\frac{(40-28) \mathrm{km}}{20 \mathrm{min}}=\frac{12 \mathrm{km}}{\frac{20}{60} \mathrm{h}}\) = 36 kmh-1, Question 4. For example, when brakes are applied to a moving truck, its velocity gradually decreases. (ii) (a) Body C. Total distance travelled = 100 – 60 = 40 cm NCERT Exemplar Class 9 Science is very important resource for students preparing for IX Board Examination. Prove that the heights reached by them would be in the ratio of \(u_{1}^{2} : u_{2}^{2}\). If extra force = F. Distance travelled by train A It is the angle which is subtended at the centre by an arc having a length equal to the radius of the circle. [NCERT Exemplar] What do you mean by 2 m/s2? To find t, use v = u + at. [NCERT Exemplar] Distance travelled by train B = Area under PQ = Area of âOPQ How does the difference in heights vary with time? Two cars arrive at certain point with velocity of 30 msâ1,25 msâ1 and travel in a straight line with uniform acceleration 0.25 msâ2 and 0.5 msâ2 respectively. If the displacement of an object is proportional to square of time, then the [â¦] Question 1. Are rest and motion absolute or relative terms? (i) The distance-time graph represents the line AB which shows the speed of the body. An electron moving with a velocity of 5 à 104 ms-1 enters into a uniform electric field and acquires a uniform acceleration of 104 ms-2 in the direction of its initial motion. What are its units? (v) Total distance travelled = 6m + 6m=12m The Car A ran for 2 minute at a speed of 7.5 km/h, slept for 56 minute and again ran for 2 minute at a speed of 7.5 km/h. Which car is the slowest? Speed = Slope of distance-time graph. Acceleration is taken as negative if it is in the direction opposite to the direction of velocity. At this point the velocity, v = u + at c) Students will be able to solve various complex situations given in standard 1 to 12 exams From the graph, it is clear that slope of distance-time graph is maximum between 10:00 AM to 10:30 AM, so the train was travelling at the highest speed during this interval of time. (NCERT Question Bank). [CDATA[ Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 9.. Her displacement-time graph is shown in figure. BC = BD + DC = BD + OA So, the distance covered in last four seconds Motion Class 9 Extra Questions HOTS (Higher Order Thinking Skills) Question 1. View Solution play_arrow. Hence, total distance, s = s1 + s2 The smaller the slope, the smaller is the speed. At 50 – 0 Which speed is greater: 30 m/s or 30 km/h? The graph given below shows the positions of a body at different times. The trains start simultaneously in the. Motion in a straight line. (i) average velocity, Here we have given HOTS Questions for Class 9 Science Chapter 6 Tissues Question⦠i.e., Average velocity = \(\frac{\text { Net displacement }}{\text { Total time taken }}\) The distance-time graph of two trains is given below. Question 4. Total distance travelled = 24 – 36 = (-) 12 cm and acceleration, a = 104ms-2 It rises to the highest point Q and returns to the same point P. What is the net displacement and distance travelled by the ball? 2. Why does the recoil of a heavy gun on firing not so strong as of a light gun using the same cartridges ? (iii) The distance-time graph represents the line CD which shows the speed of the body. What is the direction of the net force acting on the object ? Why does an athlete run a certain distance before taking a leap? We infer the motion of air by observing the movement of dust particles or leaves and branches of trees, or simply by feeling the blowing air on our face. In other words, it is under retardation. Yes, e.g. Answer: Answer: Speed = Slope of distance-time graph. If the car takes 2s to stop after the application of brakes, calculate the distance it travels during this time. What is the simplest type of motion? The various uses of a distance-time graph are as follows: Question 3. Draw a velocity versus time graph of a stone thrown vertically upwards and then coming downwards after attaining the maximum height. 2. Copy link. Answer: An athlete runs a certain distance before taking a leap so that the inertia of motion of his body at the time of leaping may help him in his muscular efforts. For motion along a straight line, when do we consider the acceleration to be (i) positive (ii) negative? It then stays in the same position for a while, eating the nuts, before returning to the tree at the same speed. Answer: Question 1. For example, suppose that a library in a city is 2 km north of the railway station. s1 = ut + \(\frac{1}{2}\) at2 or 20 = 0 + \(\frac{1}{2}\)a(2)2 or a = 10ms-2 Find the total displacement of the body from the following graph: 3. v – u = at or v = u + at, Question 2. Answer: From equations (1) and (2), Answer: What do you mean by average speed? (i) Since velocity is not changing acceleration is equal to zero. Initial velocity ,u = 0 What does the nature of the graph show ? It starts from A. The distance travelled in first 8s, Question 12. (v) Calculate the speed of the squirrel from the graph during its journey. = \(\frac{1}{2}\) à OR à OS = \(\frac{1}{2}\) à 15 ms– 1 à 5 s = 37.5 m Tap to unmute. (a) maximum distance in 3rd second? So, the motion of object Q is non-uniform. Hence, light rifle will hurt the shoulder more than the heavy rifle. Justify your answer. (Assume upward acceleration is âg and downward acceleration to be +g). No, it is always either equal to or less than the distance travelled by the object. If playback doesn't begin shortly, try restarting your device. Question 7. Answer: v2 – u2 = 0, Question 8. Is the motion of a body uniform or accelerated if it goes round the sun with constant speed in a circular orbit? (e) The slope of line graph BC represents the retardation of the body. Differentiate between distance and displacement. = 160 m + 160 m = 320 m. Question 11. (a) constant speed? So, acceleration = \(\frac{6 \mathrm{m} / \mathrm{s}}{4 \mathrm{s}}\) = 1.5 m/s Hope given HOTS Questions for Class 9 Science Chapter 9 Force and Laws of Motion are helpful to complete your science homework. Shopping. Define one radian. How much force is acting on the body ? Answer: After 2 s, height at which the second body will be = h’2 = 100 – 2g Answer: Physics Short Questions (For Class 9th) ... II- The motion of the blades of an electric fan in circular path. Radius of Semi Circular track ACB. (b) Displacement = 2 à OB Thus, the body will take 10 s to stop. [NCERT Exemplar] Answer: Where that force acts and what is the direction of that force ? RD Sharma Solutions , RS Aggarwal Solutions and NCERT Solutions, These Solutions are part of HOTS Questions for Class 9 Science. The magnitude of distance and displacement of a moving object are same when the object moves along the same straight line in the same fixed direction. This chapter is the first foundation of concepts related to motion, speed, velocity, distance, displacement, etc that will be taught in the higher classes. Question 11. Acceleration a = 0, v = u Answer: (i) Which of the bodies is moving with The data regarding the motion of two different objects P and Q is given in the following table. Eliminate t from the above equation. Answer: Answer: s = ut How much time will it take for the body to stop? (ii) The distance-time graph shows that the body is at rest between graph line B to C, it means no movement. ⢠Slope of graph is decreasing with time. Another train B is travelling on the parallel with a speed of 36 kmh-1. For train B, u = 36 kmh– 1 = 36 à \(\frac{5}{18}\) = 10 ms– 1 In this chapter, we will understand these features in detail and see how it can help us predict the future of these moving things. = Shortest distance between initial and final positions Question 24. Answer: (iv) The part CD of the graph has minimum slope, so the train had minimum speed between 11:00 AM and 11:15 AM. Answer: Question 3. Distance travelled by first body in 2 s = h1 = 0 + \(\frac{1}{2}\) g(2)2 = 2g Acceleration, a = -0.05 m/s2 (i) (a) Body A (b) Body C (c) Body B Velocity from 0 to 50 s is v1 = \(\frac{\Delta s}{\Delta t}=\frac{100-0}{50-0}\) = 2 ms-1 This can be done by obtaining the value of t from the first equation of motion. ⢠For accelerated motion. Answer: Answer: We have specified the position of the library with respect to the railway station i.e., in this case, the railway station acts as the reference point. question_answer 9) A driver takes 0.20s to apply the brakes after he sees a need for ⦠As shown in the figure, the lines BC and BE are drawn from point B on the time and the velocity axes respectively, so that the initial velocity is represented by OA, the final velocity is represented by BC and the time interval t is represented by OC. Final velocity, v= 0 (ii) average speed. III- The paths of electrons moving around the nucleus in an atom are also nearly circular. The brakes applied to a car produce an acceleration of 6 ms-2 in the opposite direction to the motion. Answer: Answer On the other hand, the object Q covers 7 m from 9:30 am to 9:45 am, 4 m from 9:45 am to 10:00 am, and so on. Accordingly the velocity-time graph is shown in figure below. [NCERT Exemplar] So the applied force on the box = 200 N. Question 2. Obtain a relation for the distance travelled by an object moving with a uniform acceleration in the interval between 4th and 5th seconds. The train stops in 5 seconds. = v à t We have been given A force of 100 N acts on a body moving with a constant velocity of 20 m s-1 on a floor in a straight line. Answer: Due to friction, its velocity decreases at the rate 0.05 m/s2. Give an example when we infer the motion indirectly. Average speed is defined as the average distance travelled per unit time and is obtained by dividing the total distance travelled by the total time taken. a = \(\frac{\mathrm{BD}}{t}\) or BD= at …..(2) So, retardation = Slope of line BC = BE/EC (b) the displacement, when it reaches B. (f) Find out the distance travelled by the body from A to B. Answer: Give an example of a body which may appear to be moving for one person and stationary for the other. A car travels at 54 km/h for first 20 s, 36 km/h for next 30 s and finally 18 km/h for next 10 s. Find its average speed. HOTS Questions for Class 9 Science: Candidates who are planning to prepare for their board examinations should take enough time for practicing HOTS Questions too. No. BD = BC – CD, represents the change in velocity in time interval t. Here, DA = 6 m/s and DE = 10 – 4 = 6 s Question 2. Here we have given HOTS Questions for Class 9 Science Chapter 9⦠(f) Distance travelled from A to B = Area under the line AB and the time axis Average velocity = 90 km/h = \(\frac{90 \mathrm{km}}{1 \mathrm{h}}\) Question 16. [NCERT Exemplar] ⢠For a body at rest. Give an example of a body in uniform acceleration. Lakhmir Singh Physics Class 9 Solutions Page No:43. To describe the position of an object we need to specify a reference point called the origin. So a force equal to the force of friction (i.e., 200 N) but opposite in direction has to be applied on the box to move it with a constant velocity. So, light rifle recoils with large velocity than the heavy rifle. Question 5. Question 6. Answer: Answer: 1. [NCERT Exemplar] (iii) Distance covered in 15 seconds = Area of ABNO Find (i) its acceleration (ii) its velocity and (iii) the distance covered by the cyclist in 15 seconds. A motorcyclist drives from A to B with a uniform speed of 30 kmh-1 and returns back with a speed of 20 kmh-1. (ii) How much distance the electron would cover in this time? Speed = \(\frac{\text { Distance }}{\text { Time }}=\frac{(7-3) \mathrm{cm}}{(9-7) \mathrm{s}}=\frac{4 \mathrm{cm}}{2 \mathrm{s}}\) = 2 cm/s, Question 3. Also initial and final velocities are equal to \(\left(g \frac{T}{2}\right)\). Answer: = Area of âORS A body starts to slide over a horizontal surface with an initial velocity of 0.5 m/s. A man walks from point A to B through semicircular track ACB as shown in figure. Answer: Similarly, distance travelled in 4 seconds, s’ = 4u + \(\frac{1}{4}\)a ⢠For decelerated (speeding down) motion. Answer: Question 2. Define acceleration and state its SI unit. Practice questions on motion Question 12 Two cars A and B race each other. But, at the same time, each passenger in a moving bus or train observes, his fellow passengers sitting and not moving. (d) Find out the acceleration of the body. (CBSE 2011, 2013), Net force acts in the direction of the force F, Since the object is not moving, so net external force acting on it is zero. Question from very important topics are covered by NCERT Exemplar Class 9.You also get idea about the type of questions and method to answer in your Class 9th ⦠Class 9 - Science - CH 8 - Motion (MCQs) Motion. = \(\frac{90 \times 1000 \mathrm{m}}{60 \times 60 \mathrm{s}}\) = 25 ms-1 (ii) v2 = u2 + 2as Therefore, time taken = \(\frac{100}{25}\) = 4 s. Question 9. Velocity is the distance travelled by the object per unit time in a given direction. What is the relation between linear velocity and angular velocity? Also find the acceleration of the car. Thus, we can tell that motion is relative. s1 = 0 + \(\frac{1}{2}\) à 5 à 82 = 160 m (ii) Reading the graph, velocity = 20 ms-1 (constant) ⢠As the slope is zero, so speed of the body is zero. Its driver applies the brakes and the train retards uniformly; train B stops in 10 seconds. [â´ F = ma]. Question 6. Their distance versus time graphs are shown in figure. Question 21. Get printable school Assignments for Class 9 Science.Standard 9 students should practise questions and answers given here for Science in Grade 9 which will help them to strengthen their understanding of all important topics. or BD = v – u …(1) No. As we know, acceleration is equal to the slope of the graph, Question 1. A car is travelling along a straight road increases its speed by unequal amounts in equal intervals of time. Answer: (ii) Part B Question 14. It is accelerated, as its velocity changes due to change in direction. Answer: Question Bank for 9th Class Science Select Chapter Matter in Our Surroundings 5 The Fundamental Unit of Life 5 Is Matter Around Us Pure 4 Force and laws of motion 14 Tissues 3 Atoms and Molecules 5 Sound 13 Diversity in Living Organisms 5 Gravitation and Floatation 17 ⦠Question 10. (ii) Name the point on the graph which is 6 m away from the base of the tree. Answer: The box will move with a constant velocity if no net external force acts on the body. Numericals The smaller the slope, the smaller is the speed. What is negative acceleration? In other words, it covers equal distance in equal interval of time. (iii) When is the train travelling at the highest speed? How much extra force is acting on the object if the object is not moving due to the application of these two forces ? (e) Calculate the retardation of the body. What is the difference between speeds of A and B? a) Helps to improve analytical skills in Class 1 to 12 students. (i) Calculate the time in which the electron would acquire a velocity double of its initial velocity. 5. s2 = 160 = vt’ + \(\frac{1}{2}\)a'(t’)2 = (20 à 4) + (\(\frac{1}{2}\)a’ à 16) â a’ = 10ms-2 A body travels along a circular path of radius 70 m. After travelling half a revolution in 20 s, find the During upward motion, acceleration = -g and during downward motion acceleration = + g. Times of upward and downward motion is equal. Question 2. These Force and Laws of Motion Class 9 Numerical will help for better concepts. Answer: The force of friction between the surface of a floor and the surface of a box in contact with the floor in 200 N. We wish to move the box on the floor with constant velocity. Express average velocity when the velocity of a body changes at a non-uniform rate and a uniform rate. Motion Class 9 Extra Questions HOTS. A particle moves in a circle with O as centre and AO = OB = 5 cm, as radius, as shown in the figure. They are relative terms. = \(\frac{1}{2}\) à OP à OQ = \(\frac{1}{2}\) à 10 ms-1 à 10 s = 50 m Recoil velocity of a gun is inversely proportional to its mass. The velocity-time graph shows the motion of a cyclist. What is essential to describe the position of an object? The Motion and Measurement of Distances Class 6 Important Questions will help students understand the new terms and their implementation in science in the higher classes. What indicates the motion of the earth? Answer: The table given below shows distance (in cm) travelled by bodies A, B and C. Read this data carefully and answer the following questions. Question 8. Answer: Answer: It measures its instantaneous speed. Question from very important topics are covered by NCERT Exemplar Class 9.. You also get idea about the type of questions and method to answer in your Class 9th ⦠Which of the trains travelled farther after the brakes were applied? (iv) At what distance does the train slow down? (i) Consider a body which starts with initial velocity u and due to uniform acceleration a, its final velocity becomes v after time t. Then, its average velocity is given by, Question 3. Acceleration = Slope of line OA = AD/OD A particle is moving in a circular path of radius r. What would be the displacement after half a circle? When do the distance and displacement of a moving object have the same magnitude? Question 6. So speed is zero i.e., (a) What type of motion is represented by OA? The nature of the graph shows that velocity changes by equal amounts in equal intervals of time. A car travels at 54 km/h for first 20 s, 36 km/h for next 30 s and finally 18 km/h for next 10 s. Find its average speed. (c) What type of motion is represented by BC? Here we have given Value Based Questions in Science for Class 9 Chapter 9 Force and Laws of Motion. Using s = ut + \(\frac{1}{2}\)at2 Answer: Answer: Four cars A, B, C and D are moving on a levelled road. (b) AB is a straight line graph between speed and time, which is parallel to the time axis (x-axis). Under what condition, the average speed is equal to the magnitude of the average velocity. Answer: If the motion is uniform, what will be the velocity after 10 s? There is no acceleration from A to B. Question 1. Answer: Note: Before looking for the solution, first try yourself, and when it becomes very difficult or if you want to check your solution, only then open the answer and explanation. You can refer to NCERT Solutions for Class 9 Science Chapter 9 Motion to revise the concepts in the syllabus effectively and improve your chances of securing high marks in your board exams. = 2 à 5 = 10 cm along AB. Also, Average velocity = \(\frac{\text { Displacement }}{\text { Time taken }}\) Speed = \(\frac{\text { Total distance }}{\text { Time }}=\frac{12}{11}\) = 1.09m/s. Answer: Suppose a squirrel is moving at a steady speed from the base of a tree towards some nuts. Distance travelled by a train and time taken by it is shown in the following table, (i) Plot distance-time graph. Acceleration of an object is said to be uniform if it travels in a straight line and its velocity increases or decreases by equal amounts in equal intervals of time.For example, motion of a freely falling body. Q 5:- How can be direction of torque found? No. Question 3. Answer: (ii) Which of the bodies covers constant velocity. In this article you will get CBSE Class 9 Science chapter, Motion: Important Questions & Preparation Tips for Semester Assessments - I 2017. Hence acceleration of body is zero. This app covers everything related to Class 9 preparation that you won't need any Class 9 online coaching or offline Class 9 coaching after having this Class 9 exam preparation app. As the motion is uniform, the velocity remains 10 m/s after 10 s. Question 18. [NCERT Exemplar] (a) OA is a straight line graph between speed and time, and it is sloping upward from O to A. Question 13. Answer: Answer: Answer: Final velocity, v = 0 and time, t = 5 s Displacement = AB i.e., Average velocity = \(\frac{\text { Initial velocity + Final velocity }}{2}\), Question 9. With the help of a graph, derive the relation v = u + at. Question 20. We need to specify a reference point called the origin. Suppose a ball is thrown vertically upwards from a position P above the ground. How much ahead of A is B when the motion starts? Write their names. In case the velocity of a body changes at a uniform rate, then the average velocity is given by the arithmetic mean of initial velocity and final [NCERT Exemplar] Given initial velocity, u = 5 à 104 ms-1 Question 1. Extra Questions for Class 9th: Ch 8 Motion (Science) Important Questions Answer Included Very Short Answer Questions (VSAQs): 1 Mark Q.1. If the velocity of a body decreases with time, then its final velocity is less than the initial velocity and thus its acceleration is negative. Speed-time graph for train A and B are shown in the figure. Four cars A, B, C and D are moving on a levelled road. How can we describe the location of an object? Answer: The driver of train A travelling at a speed of 54 kmh-1 applies brakes and retards the train uniformly. Answer: Speed is distance travelled by the object per unit time. Answer: Find (a) the total distance moved by the train, (b) the maximum speed attained by the train and (c) the position (s) of the train at half the maximum speed. How will you show that the slope of displacement-time graph gives velocity of the body ? window.__mirage2 = {petok:"a2ad84a10f5808359c943067ccf3232ea8db3177-1620637420-1800"}; Now, from the first equation of the motion, Question 3. = (s – s’) = (u + \(\frac{9}{2}\) a)m. Question 4. Substituting, BC with v and OA with u, After 2 s, height at which the first body will be = h1‘ = 150 – 2g v = 0; t = 10 s In this case, distance travelled by the object is directly proportional to the time taken. Answer: When is the acceleration taken as negative? Question 7. hero-wars.com/play_free_now. (iii) We know, speed = slope of distance-time graph. (iii) Part BC Question 23. These Solutions are part of HOTS Questions for Class 9 Science. Question 10. We have, AD = 6 m/s, and OD = 4 s [NCERT Exemplar] All the questions ⦠Name that force. s2 = 40 à 4 = 160 m (b) minimum distance in 3rd second? Answer: Uniform velocity: An object with uniform velocity covers equal distances in equal intervals of time in a specified direction, e.g., an object moving with speed of 40 kmh-1 towards west has uniform velocity. The force of friction between the surface of a floor and the surface of a box in contact with the floor in 200 N. We wish to move the box on the floor with constant velocity. Question 1. Therefore, force of friction between the body and the floor = 100 N and acts in the direction opposite to the direction of force acting on the body. Answer: = \(\frac{B D}{A D}=\frac{B D}{O C}\) Give an example of non-uniform acceleration. Since, body is moving with a constant velocity, so no net force acts on the body.
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