๐ Class 7 Science Curiosity – Chapter 8 Solutions
⏱️ Measurement of Time and Motion | Amresh Academy
๐ ๐น 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.
✅ Final Answer: 15 m/s or 54 km/h ๐
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?
➡️ Difference = 8.89 – 8 = 0.89 m/s
✅ Runner 2 is faster by 0.89 m/s ๐ฅ
3. A train travels at a speed of 25 m/s and covers a distance of 360 km. How much time does it take?
✅ Final Answer: 4 hours ๐
4. A train travels 180 km in 3 h. Find its speed in:
๐ Answer:
(i) Speed = 180 / 3 = 60 km/h
(ii) Convert → 60 × (5/18) = 16.67 m/s (approx.)
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?
➡️ 20 m/s > 18 m/s
✅ Train is faster ๐
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.
๐ Answer:
✍️ ๐น Very Short Answer Type Questions
What is the SI unit of time?
๐ Second (s) ⏱️
What does a speedometer measure?
๐ Speed of vehicle ๐
What is one oscillation of a pendulum?
๐ One complete swing ๐
Name a device used in ancient times to measure time.
๐ Sundial / water clock ⏳
What is meant by uniform motion?
๐ Equal distance in equal time
๐ง ๐น Short Answer Type Questions
What does a simple pendulum consist of?
๐ Bob + thread + support
What is the use of an odometer in vehicles?
๐ Measures total distance ๐
Why do we use quartz or atomic clocks today?
๐ High accuracy ⏱️
How was time measured before mechanical clocks were invented?
๐ Sundial, water clock, candle clock
Why is speed called a derived quantity?
๐ From distance & time
๐ ๐น Descriptive Answer Type Questions
How can you find the time period of a simple pendulum?
๐ Time for 10 oscillations ÷ 10 ⏱️
Explain the importance of accurate timekeeping in sports and medicine.
What is meant by non-uniform motion? Give one example.
What are the three main ways time is measured today?
๐ Mechanical, Quartz, Atomic clocks
How does the length of a pendulum affect its time period?
๐ Longer length → more time ⏳
๐ ๐น Exploring Questions
Why is measuring speed important in everyday life?
๐ Travel planning + safety ๐
Can the same pendulum be used at different places to measure time accurately?
๐ Slight variation due to gravity ๐
How did Galileo’s observation of a lamp lead to time measurement discoveries?
๐ Led to pendulum clocks ⏱️
What makes atomic clocks more accurate than pendulum clocks?
๐ Atomic vibrations = highly precise ⚛️
How does understanding motion help in space exploration?
๐ Accurate navigation ๐
