Kerala Syllabus Class 9 Physics - Chapter 2 Equations of Motion - Questions and Answers
Questions and Answers for Class 9 Physics ചലനസമവാക്യങ്ങൾ | Text Books Solution Physics (English Medium) Physics: Chapter 02 Equations of Motion - SAMAGRA Questions Bank
ഒമ്പതാം ക്ലാസ്സ് ഫിസിക്സിലെ Equations of Motion എന്ന പാഠം ആസ്പദമാക്കി samagra തയ്യാറാക്കിയ ചോദ്യോത്തരങ്ങള്
Class 9 Physics Equations of Motion - SAMAGRA Question Bank
∎Physics (English Medium Notes)
1. Which of the following is a vector quantity?
(distance, displacement, time, mass)
Answer: Displacement
2. What name is Negative Acceleration known by?
Answer: Retardation
3. Measurements that indicate direction along with magnitude are -----------.
Answer: Scalar quantities
4. Time is a ----------- quantity. (vector/scalar)
Answer: Scalar
5. The magnitude of displacement of an object can be equal or ----------- or ----------- to the distance travelled.
Answer: Less than, zero
6. Magnitude of displacement and distance covered are equal only when an object is moving along a straight line in the -----------.
Answer: Same direction
7. Velocity is a ----------- quantity. (vector/scalar)
Answer: Vector
8. The ----------- of velocity and displacement are the same. (direction/unit)
Answer: Direction
9. An object travelling along a circular path with constant speed always changes its -----------. (direction/mass)
Answer: Direction
10. If the direction of motion of an object with constant speed is changing, then the ----------- of the object will change. (speed/velocity)
Answer: Velocity
11. What are the quantities that can be found out from a velocity-time graph?
Answer: Displacement, acceleration, velocity, time. (any two)
12. The equations of motion are applicable only for objects in motion having ---------
Answer: Constant acceleration or uniform acceleration
13. What colour clothes are preferred in situations where you have to walk on the road in dim light?
Answer: Light colour
14. Write down the differences between distance and displacement.
Answer:
| distance | displacement |
|---|---|
| • Total length of the path travelled | • The straight line distance between two positions |
| • It cannot be zero | • It can be zero |
| • Scalar | • Vector |
15. A person is sitting at the top of a 320 m high tower. An object fell from him. How long will it take for the person to hear the sound of the object falling from the top and hitting the floor? (g = 10 m/s² , speed of sound in air = 320 m/s)
Answer:
s = ut + ½ at²
u = 0, s = 320 m, a = 10 m/s², t = ?
s = ut + ½ at²
320 = 0 X t + ½ 10 x t²
320 = 0 + 5 t²
t² = 320/5 = 64
t = 8 s
That means an object falling from the top of the tower takes 8 seconds to reach the floor.
Since the speed of sound is 320 m/s, sound takes 1 s to travel 320 m from the floor.
So it takes 8+1 = 9 s for the person above to hear the sound.
16. Write the safety rules to be followed by pedestrians and motorists to ensure road safety. (two each)
Answer:
Pedestrian:-
If there is a footpath on the side of the road, you should travel on it.
If there is no footpath, pedestrians should walk on the right side of the road.
Motorist:-
The vehicle should be driven on the left side.
Must have a driving license.
17. What is a vector quantity? Give an example.
Answer:
Vector quantities are quantities that require direction along with magnitude. Vector quantities have magnitude and direction.
Example: Displacement
18. What is a scalar quantity? Give an example.
Answer:
Scalar quantities are quantities that do not require direction.
Example: Distance
19. If a 5 m long bus crosses a 19 m long bridge with a velocity of 3 m/s, find the time taken by the bus to cross the bridge.
Answer:
s = 19 + 5 = 24 m, v = 3 m/s
v = s/t
t = s/v = 24 / 3 = 8 s
20. Calculate the displacement of a car travelling at 10 m/s in 2 minutes.
Answer:
v = s/t
s = v x t = 10 x 2 x 60 = 1200 m
21. A bullet train travels 800 km in 2 hours. Calculate the speed of the train.
Answer:
v = s/t = 800 / 2 = 400 km/hr
Or
s = 800 km = 800 x 1000 = 800000 m
t = 2 hr = 2 x 60 x 60 = 7200 s
v = 800000 / 7200 = 111.11 m/s
22. Classify the following as those with uniform velocity and non-uniform velocity.
a) A train moving at constant speed in a straight line
b) Earth's motion around the Sun
c) Light travelling through the same medium
d) Motion of a car on a busy road
Answer:
Uniform velocity: a, c
Non-uniform velocity: b, d
23. A car travelling at 20 m/s changes its velocity to 40 m/s in 4 s. Calculate the acceleration of the car.
Answer:
u = 20 m/s, v = 40m/s , t = 4 s
a = (v – u)/t = (40 – 20) / 4 = 5 m/s²
24. A car at rest started travelling in a straight line. If the acceleration of the car is 4 m/s², what is its velocity after 10 s?
Answer:
u = 0, a = 4 m/s², t = 10 s
v = u + at = 0 + 4 x 10 = 40 m/s
25. A motorcycle travelling with a speed of 5 m/s comes to rest in 5 s. Calculate the acceleration of the bike.
Answer:
u = 5 m/s, v = 0 m/s , t = 5 s
a = (v -u) / t = (0 – 5) / 5 = -1 m/s²
26. The velocity of a bus starting from rest increases to 10 m/s in 6 s. Calculate the acceleration of the bus.
Answer:
u = 0 m/s, v = 10 m/s, t = 6 s
a = (v -u) / t = (10 – 0)/6 = 1.66 m/s²
27. The acceleration of a car travelling at 5 m/s is 2 m/s² What will be the velocity of the car after 5 s?
Answer:
u = 5 m/s, a = 2 m/s², t = 5 s
v = u + at = 5 + 2 x 5 = 15 m/s
28. List the circumstances under which objects may have positive and negative acceleration.
Answer:
Positive acceleration:-
Falling stone
A train leaving the station
Negative acceleration:-
A stone is thrown up
Train arriving at the station
29. If a motorcycle travelling at a speed of 15 m/s decelerates by 2 m/s2, how much time will it take for the bike to come to rest?
Answer:
u = 15 m/s, v = 0 m/s , a = 2 m/s²
a = (v - u) / t
t = (v – u) / a = (0 – 15) / (-2) = 7.5 s
30. On the signboards installed on the roadside, warnings are given using signs like circles, triangles, squares etc. What are the warnings given by each of these?
Answer:a) Mandatory signs
b) Cautionary signs
c) Informatory signs
31. A bus travelling with a speed of 20 m/s comes to rest in 10 s. Then calculate the acceleration of the bus. How much is the retardation?
Answer:
u = 0 m/s, v = 20 m/s , t = 10 s
a = (v -u) / t = (0 – 20) / 10 = -20 / 10 = -2 m/s²
Retardation = 2 m/s²
32. Given is a diagram relating the motion of a bike. Complete the velocity-time table using the information given in the figure and sketch the velocity-time
Constructing and completing the table.Drawing the graph.
33. Observe the table.
b) By what name is this graph known?
c) From the shape of the graph obtained, write the characteristic of the object's velocity.
Answer:
a) Illustrates the graph.
b) Position–time graph
c) Uniform velocity
34. Observe the graph.
b) Find the velocity between 2 s and 6 s.
c) What is the time taken to travel 50 m?
Answer:
a) 20 m
b) 5 m/s
c) 10 s
35. A child starts from A and goes to B and then to C.
a) What is the distance travelled by the child?b) If the child then travels from C to D, does the displacement of the child make a difference? And the distance?
c) Is the displacement of the child from A through B to C positive or negative?
Answer:
a) Displacement = 20 m + 20 m = 40 m, Distance = 20 m + 20 m = 40 m
b) Distance and displacement will vary.
c) Positive
36. Given the graph relating the motion of a bike.
b) Is the motion of this bike uniform or non-uniform? Justify your answer.
Answer:
a) Acceleration is 10 m/s² during all intervals.
Eg: - A to B: Acceleration, a = v / t = 10 / 1 = 10 m/s²
b) Uniform acceleration. acceleration is equal in equal intervals.
37. An object is thrown upward from a building 80 m high with a speed of 30 m/s. (g = 10 m/s²).
a) What is the maximum height the object reaches?
b) How long will it take to reach the ground?
Answer:
a) u = 30 m/s, v = 0 m/s, a = -10 m/s²
v² = u² + 2 as
s = (v² - u²) / 2a = (02 - 302) / (2 x -10) = 45 m
Maximum height = 45 m + 80 m = 125 m
b) To reach the maximum height from the top of the building
u = 30 m/s, v = 0 m/s , a = -10 m/s²
v = u + at
t = (v – u)/a = (0 – 30)/-10 = 3 s
t1 = 3 s
To reach the ground from the maximum height
u = 0 m/s, s = 125 m , a = 10 m/s²
s = ut + ½ at²
125 = 0 + ½ x 10t²
t² = 25
t₂ = 5 s
Total time t = t₁ + t₂ = 2 + 5 = 7 s
38. A boy runs down a track 200 m long and returns to the starting position in 30 s.
a) What is the total distance travelled by the child?
b) What is the displacement of the child?
c) What is the child's speed?
d) What is the velocity of the child?
Answer:
a) 200 m
b) 0
c) speed = distance/time = 200/30 = 6.67 m/s
d) velocity = 0
39. a) Formulate the definition of distance and displacement.
b) In which case displacement of an object is zero?
c) In which case distance and displacement are equal?
Answer:
a) Writing definitions.
b) When the object returns to its original position
c) When the object travels along a straight line in the same direction
40. A person travels 100 km by car from town X to town Y. Another person travels 60 km by train on a straight track from X to Y.
a) What is the distance travelled by the car?
b) What is the displacement of the car?
c) What is the distance travelled by the train?
d) What is the displacement of the train?
Answer:
a) 100 km
b) 60 km
c) 60 km
d) 60 km
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