Motion Class 9 Numericals Physics Class 9 Motion Questions

 Physics Motion Class 9

Source - S Chand

Very Short Answer Type Questions

1. (a) What remains constant in uniform circular motion?

(b) What changes continuously in uniform circular motion?

2. State whether the following statement is true or false: Earth moves round the sun with uniform velocity.

3. A body goes round the sun with constant speed in a circular orbit. Is the motion uniform or accelerated?

4. What conclusion can you draw about the velocity of a body from the displacement-time graph shown below:

5. Name the quantity which is measured by the area occupied under the velocity-time graph.

6. What does the slope of a speed-time graph indicate?

7. What does the slope of a distance—time graph indicate?

8. Give one example of a motion where an object does not change its speed but its direction of motion changes continuously.

9. Name the type of motion in which a body has a constant speed but not constant velocity.

10. What can you say about the motion of a body if its speed-time graph is a straight line parallel to the time axis?

11. What type of motion is represented by the tip of the 'seconds' hand' of a watch ? Is it uniform or accelerated?

12. Fill in the following blanks with suitable words:
(a) If a body moves with uniform velocity, its acceleration is ----------------------.
(b) The slope of a distance-time graph indicates ----------------- of a moving body.
(c) The slope of a speed-time graph of a moving body gives its --------------------.
(d) In a speed-time graph, the area enclosed by the speed-time curve and the time axis gives the ----------------- by the body.
(e) It is possible for something to accelerate but not change its speed if it moves in a --------------------.
 

Sort Answer Type Questions

17. Is the uniform circular motion accelerated ? Give reasons for your answer.

18 Write the formula to calculate the speed of a body moving along a circular path. Give the meaning of each symbol which Occurs in it.

19. Explain why, the motion of a body which is moving with constant speed in a circular path is said to be accelerated.

20. What is the difference between uniform linear motion and uniform circular motion? Explain with examples.

21. State an important characteristic of uniform circular motion. Name the force which brings about uniform circular motion.

22. Find the initial velocity of a car which is stopped in 10 seconds by applying brakes. The retardation due to brakes is 2.5 m/s².

23. Describe the motion of a body which is accelerating at a constant rate of 10 m s2. if the body starts from rest, how much distance will it cover in 2 s ?

24. A motorcycle moving with a speed of 5 m/s is subjected to an acceleration of 0.2 m/s². Calculate the speed of the motorcycle after 10 seconds, and the distance travelled in this time.

25. A bus running at a speed of 18 km/h is stopped in 2.5 seconds by applying brakes. Calculate the retardation produced.

26. A train starting from rest moves with a uniform acceleration of 0.2 m/s² for 5 minutes. Calculate the speed acquired and the distance travelled in this time.

27. Name the two quantities, the slope of whose graph gives : (a) speed, and (b) acceleration

28. A cheetah starts from rest, and accelerates at 2 m/s² for 10 seconds. Calculate : (a) the final velocity (b) the distance travelled.

29. A train travelling at 20 m 5-¹ accelerates at 0.5 m s-² for 30 s. How far will it travel in this time?

30. A cyclist is travelling at 15 m s-¹. She applies brakes so that she does not collide with a wall 18 m away. What deceleration must she have?

31. Draw a velocity-time graph to show the following motion: A car accelerates uniformly from rest for 5 s ; then it travels at a steady velocity for 5 s.

32. The velocity-time graph for part of a train journey is a horizontal straight line. What does this tell you about -
(a) the train's velocity, and (b) about its acceleration ?
 
 
Long Answer Type Questions
 
33. (a) Explain the meaning of the following equation of motion:
v= u + at
where symbols have their usual meanings.

(b)A body starting from rest travels with uniform acceleration. If it travels 100 m in 5 s, what is the value of acceleration?

34. (a) Derive the formula : v = u + at, where the symbols have usual meanings.
(b) A bus was moving with a speed of 54 km/h. On applying brakes it stopped in 8 seconds. Calculate the acceleration.

35. (a) Derive the formula : s = ut + at=, where the symbols have usual meanings. (b) A train starting from stationary position and moving with uniform acceleration attains a speed of 36 km per hour in 10 minutes. Find its acceleration.

36. (a) Write the three equations of uniformly accelerated motion. Give the meaning of each symbol which occurs in them.
(b) A car acquires a velocity of 72 km per hour in 10 seconds staffing from rest. Find (i) the acceleration, (ii) the average velocity, and (iii) the distance travelled in this time.

37. (a) What is meant by uniform circular motion ? Give two examples of uniform circular motion.

(b) The tip of seconds' hand of a clock takes 60 seconds to move once on the circular dial of the clock. If the radius of the dial of the clock be 10.5 cm, calculate the speed of the tip of the seconds' hand of the clock (Given PI = ²²/₇.

38. Show by means of graphical method that:
v = u + at
where the symbols have their usual meanings.

39. Show by using the graphical method that:
 s = ut +¹/₂ at²
where the symbols have their usual meanings.

40. Derive the following equation of motion by the graphical method:
v² = u² + 2as
where the symbols have their usual meanings.
 
 
Multiple Choice Questions (MCQs)

41. A bus increases its speed from 36 km/h to 72 km/h in 10 seconds. Its acceleration is:
(a) 5 m/s² (b) 2 m/s² (c) 3.6 m/s² (d) 1 m/s²

42. A bus moving along a straight line at 20 m/s undergoes an acceleration of 4 cm/s². After 2 seconds, its speed will be:
(a) 8 m/s (b) 12 m/s (c) 16 m/s (d) 28 m/s

43. The slope of a speed-time graph gives:
(a) distance travelled (b) velocity (c) acceleration (d) displacement

44. The area under a speed-time graph represents a physical quantity which has the unit of:
(a) m (b) m² (c)m s-¹ (d) m s-²

45. If the displacement of an object is proportional to the square of time, then the object is moving with
(a) uniform velocity (b) uniform acceleration (6 increasing acceleration (d) decreasing acceleration