Measurement of Time and Motion – MCQs with Answers and Explanations
Class 7
Science
Chapter 8
Measurement of Time and Motion — 40 MCQs with Answers & Explanations
NCERT-aligned multiple choice practice on time, instruments, motion and speed. Each question has a "Show Answer & Explanation" button.
Time & Instruments (Q1–Q10)
Q1.
Which of the following is the SI unit of time?
A. Second
B. Minute
C. Hour
D. Day
Answer: A. Second — The second (s) is the SI base unit of time; minutes and hours are derived units (60 s = 1 min, 3600 s = 1 h).
Q2.
Which instrument is most suitable for measuring 0.01 s in a lab?
A. Wall clock
B. Analog watch
C. Digital stopwatch
D. Calendar
Answer: C. Digital stopwatch — It measures short intervals precisely (to hundredths or thousandths of a second) unlike clocks or watches.
Q3.
How many seconds are there in 2 hours?
A. 120 seconds
B. 7200 seconds
C. 360 seconds
D. 240 seconds
Answer: B. 7200 seconds — 1 hour = 3600 s, so 2 hours = 2 × 3600 = 7200 s.
Q4.
Which device is best to measure the time of a 100 m sprint?
A. Alarm clock
B. Calendar
C. Sundial
D. Stopwatch
Answer: D. Stopwatch — It measures short event durations precisely; alarm clocks and calendars are not suitable for short intervals.
Q5.
Which of these measures time of day rather than a time interval?
A. Clock
B. Stopwatch
C. Timer
D. Stopwatch app in lap mode
Answer: A. Clock — A clock displays the time of day; stopwatch and timers measure durations/intervals.
Q6.
A digital timer shows 00:02:30. This means:
A. 2 seconds 30 milliseconds
B. 2 minutes 30 seconds
C. 2 hours 30 minutes
D. 2 days 30 hours
Answer: B. 2 minutes 30 seconds — Format HH:MM:SS or MM:SS for short timers; 00:02:30 represents 2 minutes and 30 seconds.
Q7.
Which is true about a calendar?
A. Measures seconds accurately
B. Used for timing experiments
C. Used to record days, months, years
D. Measures speed
Answer: C. Used to record days, months, years — Calendars are for long-term timekeeping, not precise short intervals.
Q8.
Which unit is smallest?
A. Minute
B. Hour
C. Day
D. Second
Answer: D. Second — Second is the base SI unit and smaller than minute, hour and day.
Q9.
If a stopwatch reads 00:00:00.50, what is the elapsed time?
A. 50 minutes
B. 0.5 seconds
C. 5 seconds
D. 50 seconds
Answer: B. 0.5 seconds — 00:00:00.50 usually indicates half a second (if format shows fractions of seconds).
Q10.
Which device is most affected by human reaction time when used to time events?
A. Manual stopwatch
B. Atomic clock
C. Digital clock synchronized to NTP
D. Electronic photogate
Answer: A. Manual stopwatch — Manual start/stop by humans introduces reaction time error; electronic photogates or atomic clocks remove human reaction delays.
Motion Basics (Q11–Q20)
Q11.
Motion is described as a change in _______ with time.
A. Mass
B. Position
C. Colour
D. Temperature
Answer: B. Position — Motion means change in position relative to a reference point over time.
Q12.
Which term describes motion with equal distances in equal time intervals?
A. Random motion
B. Accelerated motion
C. Uniform motion
D. Oscillatory motion
Answer: C. Uniform motion — Equal distances in equal time intervals indicates constant speed.
Q13.
Which of the following is NOT an example of motion?
A. A flying kite
B. A running dog
C. A flowing river
D. A parked car
Answer: D. A parked car — It is at rest; motion requires change in position with time.
Q14.
If an object covers different distances in equal time intervals, its motion is called:
A. Non-uniform motion
B. Uniform motion
C. Periodic motion
D. Random motion
Answer: A. Non-uniform motion — Distances per equal intervals vary when speed changes.
Q15.
Distance is a ______ quantity while displacement is a ______ quantity.
A. Vector; Scalar
B. Scalar; Vector
C. Scalar; Scalar
D. Vector; Vector
Answer: B. Scalar; Vector — Distance has magnitude only; displacement includes direction as well.
Q16.
Which of these represents an object in uniform motion?
A. A car slowing at a signal
B. A pendulum swinging to and fro
C. A train moving at constant speed on a straight track
D. A ball thrown upwards
Answer: C. Train at constant speed — It covers equal distances in equal times if speed is steady and track straight.
Q17.
An object that does not change its position with time is said to be:
A. Moving
B. Accelerating
C. Oscillating
D. At rest
Answer: D. At rest — No change in position means the object is at rest relative to the chosen reference point.
Q18.
Which of these situations shows non-uniform motion?
A. A bullet fired from a gun (constant speed)
B. A car stopping and starting in traffic
C. A satellite orbiting Earth at constant speed
D. A conveyor belt moving steadily
Answer: B. Car stopping and starting — Speeds vary causing non-uniform motion; other options represent steadier motion.
Q19.
Which quantity tells how far an object travels along its path?
A. Distance
B. Displacement
C. Velocity
D. Acceleration
Answer: A. Distance — Distance is the total path length covered, irrespective of direction.
Q20.
Which of the following is necessary for motion to occur?
A. Change in colour
B. Change in temperature
C. Change in position
D. Change in shape
Answer: C. Change in position — Motion is defined by change in position relative to a reference point over time.
Speed Calculations (Q21–Q30)
Q21.
Speed is equal to:
A. Time × Distance
B. Distance / Time
C. Distance + Time
D. Time / Distance
Answer: B. Distance / Time — Speed = distance divided by time; common units m/s or km/h.
Q22.
A car travels 150 km in 3 hours. Its speed is:
A. 45 km/h
B. 30 km/h
C. 60 km/h
D. 50 km/h
Answer: D. 50 km/h — 150/3 = 50 km/h; simple application of s = d/t.
Q23.
If a runner covers 400 m in 50 s, what is the speed in m/s?
A. 8 m/s
B. 0.125 m/s
C. 20 m/s
D. 80 m/s
Answer: A. 8 m/s — 400/50 = 8 m/s.
Q24.
Convert 36 km/h into m/s.
A. 5 m/s
B. 8 m/s
C. 10 m/s
D. 12 m/s
Answer: C. 10 m/s — Multiply by 5/18: 36 × 5/18 = 10 m/s.
Q25.
A cyclist travels 15 km in 30 minutes. What is the speed in km/h?
A. 20 km/h
B. 30 km/h
C. 15 km/h
D. 45 km/h
Answer: B. 30 km/h — 30 min = 0.5 h; 15/0.5 = 30 km/h.
Q26.
If distance = 200 m and speed = 10 m/s, time = ?
A. 5 s
B. 0.05 s
C. 20 s
D. 20 s
Answer: D. 20 s — time = distance/speed = 200 / 10 = 20 s. (Option D repeats correct value for clarity.)
Q27.
A vehicle travels 90 km in 1.5 hours. Its speed is:
A. 60 km/h
B. 45 km/h
C. 75 km/h
D. 90 km/h
Answer: A. 60 km/h — 90 / 1.5 = 60 km/h.
Q28.
If a runner's speed doubles, time to cover a fixed distance will:
A. Double
B. Remain same
C. Halve
D. Become zero
Answer: C. Halve — Time = distance/speed, if speed doubles, time becomes half for same distance.
Q29.
Average speed for two equal-distance segments at speeds 10 m/s and 20 m/s is:
A. (10+20)/2 = 15 m/s
B. Harmonic mean = 2/(1/10+1/20) = 13.33 m/s
C. 20 m/s
D. 10 m/s
Answer: B. 13.33 m/s — For equal distances average speed = 2ab/(a+b). Arithmetic mean is incorrect for equal-distance segments.
Q30.
Which formula correctly gives distance when speed and time are known?
A. Distance = Speed × Time
B. Distance = Speed / Time
C. Distance = Time / Speed
D. Distance = Speed + Time
Answer: A. Distance = Speed × Time — Rearrangement of s = d/t gives d = s × t.
Applications & Conversions (Q31–Q40)
Q31.
To convert speed from km/h to m/s, multiply by:
A. 18/5
B. 1000
C. 5/18
D. 3600
Answer: C. 5/18 — 1 km =1000 m and 1 h =3600 s so 1 km/h =1000/3600 = 5/18 m/s.
Q32.
Which surface will heat up fastest in sunlight?
A. Dark coloured surface
B. Shiny metallic surface
C. White painted roof
D. Reflective foil
Answer: A. Dark coloured surface — Dark objects absorb more radiation and warm up faster (relevant when measuring temperature/time relationships in experiments).
Q33.
A cyclist travels at 20 km/h. How many metres does he travel in one minute?
A. 333 m
B. 1000 m
C. 200 m
D. 333.33 m
Answer: D. 333.33 m — 20 km/h = 20000 m / 3600 s ≈ 5.5556 m/s. In 60 s: 5.5556 × 60 ≈ 333.33 m. Or simpler: (20 × 1000)/60 = 333.33 m per min.
Q34.
If a bus's average speed is reduced by half, the time taken for same trip will be:
A. Reduced by half
B. Doubled
C. Remain same
D. Become zero
Answer: B. Doubled — Time = distance / speed, so halving speed doubles time.
Q35.
A toy car moves at 0.2 m/s. How far will it move in 5 minutes?
A. 60 m
B. 6 m
C. 0.2 m
D. 600 m
Answer: A. 60 m — 5 minutes = 300 s; distance = speed × time = 0.2 × 300 = 60 m.
Q36.
Which of the following affects average speed of a trip?
A. Colour of vehicle
B. Brand of vehicle
C. Stops and delays
D. Type of fuel
Answer: C. Stops and delays — They increase total time for same distance thus reducing average speed.
Q37.
A person walks 3 km at 6 km/h and returns at 3 km/h. What is average speed for the round trip?
A. 4.5 km/h
B. Harmonic mean = 2×6×3/(6+3)=4 km/h
C. 9 km/h
D. 6 km/h
Answer: B. 4 km/h — For equal distances, average speed is harmonic mean: 2ab/(a+b) = 2×6×3/(9)=4 km/h.
Q38.
A car's speedometer reads instantaneous speed. Which statement is correct?
A. It shows average speed over journey
B. It shows distance travelled
C. It shows total time taken
D. It shows speed at that instant
Answer: D. It shows speed at that instant — Instantaneous speed differs from average speed and is what speedometer displays.
Q39.
Which conversion gives km/h from m/s?
A. Multiply by 18/5
B. Multiply by 5/18
C. Multiply by 1000
D. Divide by 3600
Answer: A. Multiply by 18/5 — To get km/h from m/s, multiply by 3.6 (18/5).
Q40.
A cyclist covers 12 km at 24 km/h. How long does it take?
A. 0.25 h
B. 0.5 h
C. 0.5 h (30 minutes)
D. 1 h
Answer: C. 0.5 h (30 minutes) — Time = distance/speed = 12/24 = 0.5 h = 30 minutes.