Chapter Motion: Class 9 - Physics - Short Questions and Answers - Part-1
Q1: An object has moved through a distance. Can it have zero displacements? If yes, support your answer with an example.
Answer: Yes, even if an object has moved through a distance, it can have zero displacements. For example, an object after moving through a certain distance (say d), comes back to its starting position. In that case, the distance covered is 2d while displacement is zero.
Q2: Is displacement a scalar quantity?
Answer: No, displacement is a vector quantity because it has magnitude as well as direction.
Q3: State whether the distance is a scalar or a vector quantity.
Answer: Distance is a scalar quantity; it has magnitude but no specific direction.
Q4: Change the speed from 9 m/s to km/h.
Answer: 9m/s = 9 × 3600 / 1000 = 32.4 km/h
Q5: If a body moves with uniform velocity, what will be its acceleration?
Answer: Zero
Q6: Can the magnitude of a displacement be greater than the distance travelled by the object?
Answer: No.
Q7: What does the odometer of an automobile measure?
Answer: The odometer of automobile measures the distance travelled by automobile (or vehicle).
Q8: What name is given to the speed in a specified direction?
Answer: Velocity is the name given to the speed of a body in a particular direction.
Q9: Give two examples of bodies having non-uniform motion.
Answer: Two examples of non-uniform motion:
i. A car moving on a busy road
ii. A bee flying randomly in the air.
Q10: Name the physical quantity obtained by dividing 'Distance travelled' by 'Time is taken to travel that distance.
Answer: Speed is obtained by dividing 'distance travelled' by 'time taken to travel that distance.
Q11: A Mango tree is standing at the corner of the park.
Ramesh says, "Since the Mango tree does not move, it is at rest."
Suresh says, "Since the earth is moving, the tree is also moving."
Who is making the correct statement? What do you infer?
Answer: Both statements are correct. Motion and rest are relative terms.
Q12: What do the following measure in a car?
a Speedometer
b Odometer
Answer:
a. Speedometer of a car is used to measure the instantaneous speed of the car.
b. Odometer of a car is used to record and measure the overall distance travelled by the car.
Q13: When do the distance and magnitude of displacement become equal?
Answer: Distance and magnitude of displacement become equal when an object is travelling in a straight path that is a rectilinear path in the same direction.
Q14: Are distance and displacement time-independent or time-dependent quantities?
Answer: Generally the distance covered and displacement are time-dependent quantities.
Q15: Give an example of a physical quantity which is time-independent.
Answer: mass
Q16: Name the physical quantity which gives us an idea of how slow or fast a body is moving.
Answer: Speed is the physical quantity that gives the idea of how slow or fast a body is moving.
Q17: When is a body said to have uniform velocity?
Answer: When a body covers equal distances in equal intervals of time in a particular direction, it is said to have uniform velocity.
Q18: In addition to speed if we know the direction of a moving object, then it is called?
Answer: Velocity
Q19: Which is a vector quantity between velocity and speed?
Answer: Velocity.
Q20: When is a body said to have uniform velocity?
Answer: When a body covers equal distances in equal intervals of time in a particular direction, it is said to have uniform velocity.
Q21: A scooterist covers a distance of 3 kilometres in 5 minutes. Calculate his speed in metres per second (m/s).
Answer: Distance travelled = 3 km = 3000m
Time = 5 min = 5 × 60 = 300s
Speed = Distance / time = 3000 / 300 = 10 m/s
Q22: If an object covers s₁ distance in t₁ time and then covers s₂ distance in t₂ time. What is its average speed?
Answer:
Total distance s₁ + s₂ Avg Speed = ---------------- = ---------- Total Time t₁ + t₂
Q23: Can speed be negative?
Answer: No.
Q24: Can velocity is negative?
Answer: Yes.
Q25: Under which condition is the magnitude of average velocity equal to average speed?
Answer: The magnitude of average velocity is equal to average speed when an object covers equal distances in equal intervals of time in a particular direction
☞See also:
Ch 8 - Motion (Q &A)
Ch8 - Motion (Worksheet)
Ch8 - Motion (MCQs)
Ch 8 - Motion (Assignment)
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