PHYSICS STD 9 ICSE ( ) MOTION IN ONE DIMENSION

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Silas Webb
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PHYSICS STD 9 ICSE (2017-2018) MOTION IN ONE DIMENSION IMPORTANT FORMULAE 1. Speed = Distance Time or v = S t 2. Average speed = Total distance travelled Total time taken 3.

Equations of motion: (i) v = u + at (ii) v 2 u 2 = 2aS (iii) S = ut + 1 2 at2 where, u = initial velocity v = final velocity a = acceleration S = distance travelled t = time of journey SECTION A

1 PHYSICS STD 9 ICSE ( ) MOTION IN ONE DIMENSION IMPORTANT FORMULAE 1. Speed = Distance Time or v = S t 2. Average speed = Total distance travelled Total time taken 3. Average velocity = Displacement Total time taken 4. Average velocity = Initial velocity +Final velocity 2 5. Acceleration = Change in velocity time interval or a = v u t or v = u + at 6. Equations of motion: (i) v = u + at (ii) v 2 u 2 = 2aS (iii) S = ut at2 where, u = initial velocity v = final velocity a = acceleration S = distance travelled t = time of journey SECTION A QUESTION BANK Q.1.A train is moving out of a railway station. Is the platform at rest or in motion with respect to the train? Q.2.Are the passengers of a moving bus at rest or in motion with respect to each other. Q.3. Classify the following into scalar and vector quantities: Speed, Velocity, Mass, Displacement, Acceleration, Distance,Retardation Q.4.Write three points of difference between distance and displacement. 1

2 Q.5.Under what conditions is the displacement of a body equal to the distance travelled by it? Q.6.A body is moving along a circular path of radius R. What will be the distance and displacement of the body when it completes (i). One revolution (ii). Half a revolution Q.7.A man travels a distance of 1.5 m towards the east, then 2.0 m towards the south and finally 4.5 m towards the east in 4 seconds. Calculate: (a) The total distance travelled and (b) the final displacement. Q.8.The figure shown alongside shows the path travelled by a person from his house to the market (a) Calculate the total distance travelled by him. (b) Calculate the resultant displacement. Q.9. Arrange the following in an increasing order: 18 km / h, 7 m / s, 2000 m / min. Q.10. A scooter acquires a speed of 36 km/h in 10 s after the start. Calculate the acceleration of the scooter. Q.11.When do the velocity and speed of a moving body become identical? Q.12. Define the acceleration of a body. What is its unit? Q. 13.Give one example of a body moving with uniform velocity. Q.14. Give one example of a uniformly accelerated motion. Q.15.A body goes from A to B with a speed of 60 km / h and returns to the starting point with a speed of 40 km / h. Find (i) the average speed (ii) the average velocity of the body. Q.16.Find the initial velocity of a car which is stopped in 10 s by applying brakes. Retardation due to brakes is 2.5 m / s 2. Q.17. Complete the following table: Quantity C.G.S. unit S.I. unit Scalar or Vector Speed Velocity Q.18. Give an example of a motion in which the average velocity is zero, but the average speed is not zero. 2

3 Q.19. Give two differences between speed and velocity. Q.20. Define uniform acceleration and non uniform acceleration. Give one example of each. Q.21.In a long distance race, the racing cars were expected to take 12 rounds of the track where the line of finish was the same as the line of start. The length of the track is 2000 m. (i) What is the total distance to be covered by the racing cars? (ii) What is the displacement of the racing cars when they touch the finish line? (iii) Is the motion of the cars uniform or non uniform? Q.22.The table below shows the distance, in cm, travelled by objects A, B and C during each second. Time Distance covered per second by A, B and C ( second) Object A (cm) Object B (cm) Object C (cm) 1 st nd rd th th (i) (ii) (iii) Which object is moving with constant speed? Give a reason for your answer. Which object is moving with constant acceleration? Give the value of this acceleration. Which object is moving with an irregular acceleration? Q.23.Give an example of a motion in which speed is constant, but velocity is variable. Q.24.Differentiate between acceleration and retardation. SECTION B Q.1. The graph given here shows the positions of the body at different times. What is the speed of the body as it moves from B to C. Q.2 Which of the two bodies has greater speed? See the figure. 3

4 Q.3. Explain the difference between the two graphs shown in I and II. I II Q.4.What conclusion can you draw from the graphs shown below? I. II. Q.5.State the type of motion indicated by the following velocity vs time graphs. I II III IV V VI 4

5 Q.6.Which graph in the figures given below is closest to the velocity-time graph of a stone which is thrown straight up into the air at time t = 0 and returns to the earth at t = t1? Q.7. (i).what does the slope of a velocity time graph represent? (ii).what does the area enclosed between the graph and the time axis in a velocity time graph represent? Q.8.What can you conclude from the following graphs about the state of motion of an object? (i). Displacement time graph is parallel to the time axis. (ii). Velocity time graph is a straight line making an angle with the time axis. Q.9.Draw displacement time graphs for the following situations: (i) When a body is stationary. (ii) When a body is moving with uniform velocity. (iii) When a body is moving with variable velocity. SECTION C Q.1.Brakes applied to a car produce a uniform retardation of 90 cm / s 2. If the car was travelling with a velocity of 27 m / s, then what distance will it cover before coming to rest. Q.2.A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m /s, with what velocity will it strike the ground? Q.3.A body is thrown up with a velocity of 20 m/s. It retards uniformly at the rate of 10 m/s 2 Find the velocity of the body after 2 s. Q.4.Derive the equations: (i) v = u + at (ii) v 2 u 2 = 2aS (iii) S = ut at2 Q.4.A train starts from rest and accelerates uniformly at a rate of 2 ms -2 for 10 s. It then maintains a constant speed for 200 s.the brakes are then applied and the train is uniformly retarded and comes to rest in 50 s.find 5

6 (i) The maximum velocity reached (ii) the retardation in the last 50 s. (iii) The total distance travelled (iv) the average velocity of the train. Q.5.Explain the term acceleration due to gravity. Q.6.A stone and a pencil are released simultaneously in vacuum from the top of a tower. Which of the two will reach the ground first? Give reason to your answer. Q.7.A stone dropped in a well takes 3 s to reach the surface of water. Take g = 10 m / s 2. Calculate: (i) The depth of the well (ii) the velocity with which the stone strikes the surface of water. Q.8.A car moving with a velocity 20 m / s is brought to rest by applying the brakes in 5 s. Calculate :(i).the retardation (ii).the distance travelled by the car Q.9.A bullet initially moving with a velocity 20 m/s strikes a target and comes to rest after penetrating a distance 10 cm in the target. Find the retardation caused by the target. Q.10.A ball is dropped from the top of a tower. It acquires a velocity 20 m / s on reaching the ground. Calculate the height of the tower. (g = 10 m / s 2 ) Q.11.A body with an initial velocity of 18 km / h accelerates uniformly at the rate of 9 cm / s 2 over a distance of 200 m. Calculate : (i) the acceleration in m /s 2 (ii) Its final velocity in m / s. Q.12. A body moving with uniform acceleration travels 84 m in 6 s and 264 m in 11 s. Find: (i) The initial velocity (ii) The acceleration of the body. 6

Motion in one dimension

Motion in one dimension Work Sheet - 1 1. Define rest and motion. 2. Define distance and displacement. Write their S.I unit. 3. Distinguish between distance and displacement. Write five points of differences. Work Sheet - 2 1.