by Tiwari Academy
NCERT Solutions for Class 7 Science Curiosity Chapter 8 Measurement of Time and Motion for Session 2025-26. It provides comprehensive answers to textbook questions, helping students understand concepts like time measurement, types of clocks, the pendulum and uniform and non-uniform motion. These solutions explain the relationship between speed, distance and time with practical examples and calculations. NCERT Curiosity Solutions support conceptual clarity and problem-solving skills, making learning engaging, accurate and useful for both academic and real-life applications.
Class 7 Science Solutions
Class 7 Science Curiosity Chapter 8 Solutions
Let Us Enhance Our Learning
1. Calculate the speed of a car that travels 150 metres in 10 seconds. Express your answer in km/h.
See AnswerDistance = 150 m
Time = 10 s
Speed = Distance/Time
= 150 m/10 s
= 15 m/s
Conversion to km/h:
15 m/s x (18/5)
= 54 km/h
The speed of the car is 15 m/s or 54 km/h.
2. A runner completes 400 metres in 50 seconds. Another runner completes the same distance in 45 seconds. Who has a greater speed and by how much?
See AnswerRunner 1: Speed = 400 m/50 s = 8 m/s
Runner 2: Speed = 400 m/45 s = 8.89 m/s (approx.)
Comparison: Runner 2 has a greater speed.
Difference = 8.89 m/s – 8 m/s = 0.89 m/s (approx.)
The second runner (who took 45 seconds) has a greater speed by approximately 0.89 m/s.
3. A train travels at a speed of 25 m/s and covers a distance of 360 km. How much time does it take?
See AnswerSpeed = 25 m/s
Distance = 360 km = 360,000 m
Time = Distance / Speed = 360,000 m/25 m/s = 14,400 s
Conversion to hours: 14,400 s/3600 s/h = 4 h
The train takes 4 hours.
4. A train travels 180 km in 3 h. Find its speed in: (i) km/h (ii) m/s (iii) What distance will it travel in 4 h if it maintains the same speed throughout the journey?
See Answer(i) Speed in km/h
= 180 km/3 h
= 60 km/h
(ii) Speed in m/s
= 60 km/h x (5/18)
= 16.67 m/s (approx.)
(iii) Distance in 4 h
= Speed x Time
= 60 km/h x 4 h
= 240 km
5. The fastest galloping horse can reach the speed of approximately 18 m/s. How does this compare to the speed of a train moving at 72 km/h?
See AnswerHorse Speed = 18 m/s
Train Speed = 72 km/h
Convert train speed to m/s: 72 km/h x (5/18) = 20 m/s
Comparison: 20 m/s > 18 m/s
The train’s speed (20 m/s) is greater than the horse’s speed (18 m/s).
6. Distinguish between uniform and non-uniform motion using the example of a car moving on a straight highway with no traffic and a car moving in city traffic.
See AnswerUniform Motion: Constant speed along a straight line. Example: Car on an empty straight highway maintaining 80 km/h. Covers equal distances in equal times.
Non-uniform Motion: Changing speed along a straight line. Example: Car in city traffic speeding up, slowing down, stopping. Covers unequal distances in equal times.
Class 7 Science Curiosity Chapter 8 Very Short Answer Type Questions
What is the SI unit of time?
See AnswerThe SI unit of time is the second, symbolized as s.
What does a speedometer measure?
See Answer A speedometer measures the speed of a vehicle in km/h.
What is one oscillation of a pendulum?
See Answer One oscillation is when the pendulum bob moves from its mean position to both extreme ends and back.
Name a device used in ancient times to measure time.
See Answer Sundial, hourglass, water clock, or candle clock.
What is meant by uniform motion?
See AnswerMotion in which equal distances are covered in equal intervals of time.
Class 7 Science Curiosity Chapter 8 Short Answer Type Questions
What does a simple pendulum consist of?
See Answer A simple pendulum consists of a small metal ball (bob) tied to a long thread fixed to a rigid support, allowing it to oscillate back and forth.
What is the use of an odometer in vehicles?
See Answer An odometer measures the total distance travelled by a vehicle in kilometres.
Why do we use quartz or atomic clocks today?
See AnswerQuartz and atomic clocks are highly accurate and can measure time precisely to the fraction of a second, unlike older mechanical clocks.
How was time measured before mechanical clocks were invented?
See AnswerTime was measured using natural cycles and devices like sundials, water clocks, candle clocks, and hourglasses.
Why is speed called a derived quantity?
See AnswerSpeed is derived from the base quantities—distance (metres) and time (seconds), and is calculated as distance divided by time.
Class 7 Science Curiosity Chapter 8 Descriptive Answer Type Questions
How can you find the time period of a simple pendulum?
See AnswerMeasure the time taken for 10 complete oscillations using a stopwatch and divide that time by 10. The resulting value is the time period of the pendulum. Repeating this multiple times ensures accuracy and shows that the time period remains constant if the length is unchanged.
Explain the importance of accurate timekeeping in sports and medicine.
See AnswerAccurate timekeeping is crucial in sports to differentiate winners by milliseconds. In medicine, devices like ECG machines detect heart problems by tracking millisecond variations. Such precision also improves technology and scientific research.
What is meant by non-uniform motion? Give one example.
See AnswerNon-uniform motion occurs when an object covers unequal distances in equal intervals of time. For example, a car moving through city traffic changes speed frequently and is thus in non-uniform motion.
What are the three main ways time is measured today?
See AnswerTime is measured using mechanical clocks (like pendulum clocks), quartz clocks (using vibrating crystals), and atomic clocks (using vibrations of atoms), with increasing accuracy from mechanical to atomic.
How does the length of a pendulum affect its time period?
See AnswerThe time period of a pendulum increases with its length. Longer pendulums swing slower. This relationship helps design clocks and experiments involving oscillations.
Class 7 Science Curiosity Chapter 8 Exploring Questions
Why is measuring speed important in everyday life?
See Answer Speed tells us how quickly something moves. It helps us estimate travel time, schedule transportation, ensure safety in driving, and evaluate performance in sports. Without speed measurements, planning and navigation would be difficult.
Can the same pendulum be used at different places to measure time accurately?
See AnswerThe time period depends on the length and gravity at a location. So, the same pendulum may show slight differences in time at different altitudes due to changes in gravity.
How did Galileo’s observation of a lamp lead to time measurement discoveries?
See AnswerGalileo noticed that a swinging lamp in a church took equal time to complete each swing. This inspired him to experiment with pendulums and discover their consistent oscillation, forming the basis for pendulum clocks.
What makes atomic clocks more accurate than pendulum clocks?
See Answer Atomic clocks use the constant frequency of atomic vibrations (like cesium atoms), which are not affected by temperature or gravity, unlike pendulums, making them far more precise.
How does understanding motion help in space exploration?
See AnswerSpacecraft movement depends on precise timing and speed calculations. Understanding motion allows scientists to navigate, land probes and launch missions with extreme accuracy across millions of kilometres.
How did people measure time before the invention of clocks, as explained in Class 7 Science Curiosity Chapter 8?
In Class 7 Science Curiosity Chapter 8, it is explained that long before mechanical or digital clocks, people relied on natural and manual devices to measure time. They observed repeating natural events like sunrise, sunset and moon phases. They invented tools such as sundials, which used the position of shadows, water clocks, where water flowed at a steady rate and candle clocks, marked with time intervals. Although not highly accurate, these devices helped in estimating smaller intervals of time. Over time, these evolved into more precise instruments like hourglasses and eventually mechanical clocks.
What is the relationship between speed, distance and time in Class 7 Science Curiosity Chapter 8?
Class 7 Science Curiosity Chapter 8 introduces the formula:
Speed = Distance ÷ Time.
This helps us calculate how fast an object is moving. If we know any two quantities (distance and time or speed and time), we can calculate the third. For instance, if a car travels 100 km in 2 hours, its speed is 50 km/h. Similarly, knowing speed and time allows us to find the distance. This relationship is widely used in sports, travel planning and science. The chapter also explains that speed may vary and in most cases, we calculate average speed over a journey.
Why is the simple pendulum important in understanding time, as discussed in Class 7 Science Curiosity Chapter 8?
According to Class 7 Science Curiosity Chapter 8, the simple pendulum played a useful role in the history of timekeeping. A pendulum swings back and forth in a fixed, regular rhythm called oscillation. The time taken for one complete swing is called its time period. Galileo observed that a pendulum of fixed length takes equal time for each swing, regardless of how heavy the bob is. This led to the invention of the pendulum clock by Christiaan Huygens. Pendulums showed that time could be measured using consistent, repeating motion, laying the foundation for accurate mechanical clocks.
Why do we study time and motion in Class 7 Science Curiosity Chapter 8?
In Chapter 8, we learn how to measure time and understand movement, which helps us in daily life – whether it’s checking speed, catching a train or measuring a runner’s performance. The chapter introduces basic tools like pendulums, clocks, speedometers and odometers and shows how to calculate speed using the distance ÷ time formula. These are skills we use every day without even realising it.
Is it difficult to understand the pendulum and its time period in Class 7 Science Curiosity Chapter 8?
Not at all! Class 7 Science Curiosity Chapter 8 explains the pendulum through simple experiments. One oscillation means a full back-and-forth swing. The time period is how long one oscillation takes. Just remember: measure time for 10 oscillations and divide it by 10. It’s easier if you try the activity at home or in school with thread and a small weight.
How can I do well in Class 7 Science Curiosity Chapter 8 without getting confused by formulas?
Focus on understanding the concepts first—like what motion is, how we measure distance and time, and how speed is calculated. Use the speed = distance ÷ time formula in real-life examples like walking, running or cycling. Practice with simple values and make a chart of units (like m/s or km/h) to avoid confusion. Once you connect it to everyday life, the formulas become easy.
