Extra Questions for Chapter 8 Measurement of Time and Motion Class 7 Science Curiosity
Class 8 Measurement of Time and Motion Extra Questions
Very Short Answer Questions
Question 1. What is the basic unit of speed?
Answer
The basic unit of speed is the metre per second (m/s).
Question 2. What is oscillatory motion?
Answer
The to and fro motion of an object is known as oscillatory motion.
Question 3. What do you mean by the statement; “car is moving with the speed of 50 Km per hour”?
Answer
Car is moving with the speed of 50 Km per hour it means it will cover a distance of 50 Km in one hour
Question 4. What is motion?
Answer
Motion is a change in the position of an object with time.
Question 5. What is a simple pendulum's periodic motion?
Answer
A simple pendulum's periodic motion involves oscillations back and forth from a centre point.
Question 6. What information can be interpreted from a distance-time graph?
Answer
A distance-time graph shows how distance changes over time and helps determine the speed of a moving object.
Question 7. How do you define uniform motion?
Answer
Uniform motion occurs when an object moves along a straight line with a constant speed.
Question 8. What is the time period of a simple pendulum?
Answer
The time period of a simple pendulum is the time taken for the pendulum to complete one full oscillation.
Question 9. How is non-uniform motion different from uniform motion?
Answer
In non-uniform motion, the speed or direction of the object changes, whereas in uniform motion, the speed remains constant.
Question 10. How do we measure speed using a speedometer and an odometer?
Answer
Speedometers measure and display the speed of a vehicle in km/h, while odometers record the distance travelled by the vehicle in kilometres (km).
Question 11. Give an example of oscillatory motion.
Answer
To and fro motion of a simple pendulum.
Question 12. What is uniform motion?
Answer
Uniform motion is when an object covers equal distances in equal intervals of time.
Question 13. Name the device used to measure speed.
Answer
Speedometer
Question 14. What is non-uniform motion?
Answer
Non-uniform motion is when an object covers unequal distances in equal intervals of time.
Question 15. What is speed in the context of motion?
Answer
Speed is the distance covered by an object in a unit of time. It measures how fast or slow an object is moving.
Question 16. Define average speed.
Answer
Average speed is the total distance covered by an object divided by the total time taken for the journey.
Question 17. What is the basic unit of time?
Answer
The basic unit of time is the second (s).
Question 18. Which unit is used to measure speed in the metric system?
Answer
Speed is measured in meters per second (m/s) in the metric system.
Question 19. What is a speedometer, and what is its purpose?
Answer
A speedometer is an instrument used in vehicles to display the vehicle's speed. It shows how fast the vehicle is moving.
Question 20. How are large speeds commonly measured?
Answer
Large speeds are commonly measured in kilometres per hour (km/h).
Question 21. Define uniform motion.
Answer
Uniform motion refers to the motion of an object in a straight line at a constant speed, covering equal distances in equal intervals of time
Question 22. What is non-uniform motion?
Answer
Non-uniform motion is the motion in which the speed of an object varies, i.e., it does not move at a constant speed.
Question 23. What is oscillation in the context of time?
Answer
Oscillation refers to the repeated back-and-forth or to-and-fro motion of an object around a central position.
Question 24. How is the time period of a pendulum defined?
Answer
The time period of a pendulum is defined as the time it takes to complete one full oscillation.
Short Answer Questions
Question 1. When pendulum is said to have one complete oscillation?
The pendulum is said to have completed one oscillation when its bob, starting from its mean position B, moves to A, to C and back to B.
Question 2. What is non-uniform motion?
Non-uniform motion occurs when an object's speed changes while moving along a straight line.
It means:
- The speed is not constant.
- Motion can vary from slow to fast.
- It contrasts with uniform motion, where speed remains constant.
Question 3. What is uniform motion?
Answer
An object that moves in a straight line at a constant speed is described as being in uniform motion.
It means:
- The speed does not change over time.
- The distance covered is proportional to the time taken.
- The motion can be represented by a straight line on a distance-time graph.
Question 4. Explain the concept of speed and how it is calculated.
Answer
Speed is the measure of how fast or slow an object is moving. It is calculated by dividing the distance covered by the object by the time taken.
The formula for speed is, Speed = Distance/Time.
Question 5. Define average speed.
Answer
The average speed of a moving object is defined as the total distance covered by it divided by the total time taken.
Question 6. What is speedometer?
Answer
A speedometer is a device that measures and displays the speed of a vehicle.
- It is commonly found on the dashboards of cars, motorcycles, and scooters.
- The speed is usually shown in kilometres per hour (km/h).
- Speedometers help drivers maintain safe speeds while driving.
Question 7. What is non-uniform linear motion? Give one example.
Answer
Non-uniform linear motion is when an object moves in a straight line but its speed changes, covering unequal distances in equal times.
Example: A car slowing down at a traffic light.
Question 8. Describe the purpose and function of a speedometer and an odometer in vehicles.
Answer
A speedometer is an instrument that shows how fast a vehicle is travelling. It helps the driver maintain a safe speed while driving. An odometer measures the total distance a vehicle has travelled over time. This information is useful for keeping track of mileage for maintenance and service schedules.
Question 9. What is an hourglass, and how does it measure time?
Answer
An hourglass is a device with two glass bulbs connected by a narrow neck, filled with sand. The sand flows from the top bulb to the bottom, and the time it takes to empty the top bulb shows a fixed amount of time, like an hour.
Question 10. What are quartz clocks?
Answer
Quartz clocks are timekeeping devices that use an electric circuit powered by one or more cells.
- They are known for their high accuracy in measuring time.
- Quartz clocks have largely replaced older clock technologies.
- The precision of quartz clocks is significantly better than traditional clocks.
Question 11. What is distance-time graph?
Answer
A distance-time graph visually represents how far an object travels over time.
Its significance:
- It shows the speed of an object.
- A straight line indicates constant speed.
- If the line is curved, the object's speed is changing.
Question 12. A simple pendulum takes 32 s to complete 20 oscillations. What is the time period of the pendulum?
Answer
Number of oscillations = 20
Total time taken to complete 20 oscillations = 32 s
Question 13. Explain how in ancient time a day, a month and a year were measured?
Answer
Our ancestors observed that many natural events occur at regular intervals:
- The day was defined as the time between one sunrise and the next.
- A month was measured from one new moon to the next.
- A year was determined by the time it takes for the Earth to complete one revolution around the sun.
Question 14. The distance between two stations is 240 km. A train takes 4 hours to cover this distance. Calculate the speed of the train.
Answer
Distance between two stations = 240 km
Time taken to cover this distance = 4 hours
Question 15. Define the time period of a pendulum and explain its significance.
Answer
The time period of a pendulum is the duration it takes to complete one full swing back and forth. This is significant because:
- The time period remains constant for a pendulum of a specific length.
- In pendulum clocks, this consistency allows them to be accurate timekeepers.
- Understanding the time period helps in designing and improving time-measuring devices.
Question 16. Differentiate between uniform motion and non-uniform motion with examples.
Answer
Uniform motion occurs when an object travels in a straight line at a constant speed, covering equal distances in equal time intervals. For example:
- A car moving on a straight road at a steady 60 km/h.
Non-uniform motion happens when the speed of an object changes during its movement. For instance:
- A car slowing down as it approaches a traffic light.
Question 17. What are the basic units for time and distance? How is speed measured?
Answer
The basic unit for time is the second (s), while the basic unit for distance is the meter (m).
Speed is calculated using the formula:
Speed = Distance/Time
It is typically measured in meters per second (m/s).
Question 18. Explain the concept of oscillation and provide an example.
Answer
Oscillation is the motion of an object moving back and forth around a central point. Key points include:
- It involves a repetitive movement.
- An example is a pendulum that swings from one side to the other.
- Each complete swing from one side to the other and back is called one oscillation.
In summary, oscillation is a common type of motion seen in various systems, such as pendulums and springs.
Question 19. How do natural events and man-made structures help in measuring time?
Answer
Natural events and man-made structures are essential for measuring time.
- Natural events include the phases of the moon, which help track months.
- Man-made structures like sundials indicate the time of day by showing the sun's shadow.
- For example, the position of the shadow on a sundial reveals the current hour.
Question 20. What are graphs, and why are they useful in representing data?
Answer
Graphs are visual tools that represent numerical data, making it easier to understand and compare information. They are beneficial because:
- They provide a visual representation of data.
- They simplify the process of interpreting and analysing information.
- They allow for quick comparisons between different data sets.
Question 21. Name and briefly describe the three types of graphs.
Answer
The three types of graphs are:
- Bar graphs: These use horizontal or vertical bars to display numerical comparisons.
- Pie charts: Circular graphs that illustrate relative percentages or shares of a whole.
- Line graphs: These connect data points with lines to show how one quantity changes in relation to another.
Question 22. Explain how the shape of a graph differs for a body in uniform motion, a body at rest, and a body in non-uniform motion.
Answer
- Body in uniform motion: The graph is a straight line that slopes upwards, indicating constant speed.
- Body at rest: The graph is a horizontal line along the X-axis, showing zero speed.
- Body in non-uniform motion: The graph is curved or zigzagged, reflecting changes in speed.
Question 23. What is the difference between an odometer and a speedometer? Give an example of how each is used.
Answer
An odometer measures the total distance a vehicle travels in kilometres, while a speedometer shows how fast the vehicle is moving in km/h. For example, if you drive to a park, the odometer might show you’ve gone 20 km, helping you know when to service the car.
The speedometer might show 40 km/h, helping you drive safely within the speed limit.
Question 24. Salma takes 15 minutes from her house to reach her school on a bicycle. If the bicycle has a speed of 2 m/s, calculate the distance between her house and the school.
Answer
Time taken = 15 min = 15×60 = 900 seconds
Speed = 2 m/s
Distance = Speed × Time = 2×900 = 1800 m
In km, 1800/1000 = 1.8 km
Long Answer Questions
Question 1. Give an example of oscillatory motion.
Answer
The to and fro motion of a simple pendulum is a clear example of oscillatory motion.
Its significance:
- A simple pendulum consists of a small weight, known as the bob, attached to a string or thread.
- When the bob is pulled to one side and released, it swings back and forth around its mean position.
- This back-and-forth movement is repeated in a regular pattern, making it a periodic motion.
Question 2. Calculate the speed of a car that travels 150 meters in 10 seconds. Express your answer in km/h.
Answer
Speed = Distance/Time
Given:
Distance = 150 meters
Time = 10 seconds
Convert meters to kilometres and seconds to hours:
Question 3. An object moving along a straight line with a constant speed is said to be in uniform motion.
Answer
Vehicle A is moving faster. The speed of a vehicle is determined by the distance it covers in a specific time frame.
It means:
- A vehicle that travels a greater distance in the same time interval has a higher speed.
- For example, if Vehicle A covers 100 metres in 5 seconds and Vehicle B covers 80 metres in the same time, Vehicle A is faster.
- Speed can vary; the same vehicle may move faster or slower at different times.
Question 4. Differentiate between circular motion and periodic motion.
Answer
Circular Motion: Motion of an object in a circular path is called circular motion. For example: Motion of the hands of a clock.
Periodic Motion: When an object repeats its motion after some time. This type of motion is called periodic motion. For example: Motion of a pendulum, motion of a child on a swing, motion of the strings of a guitar.
Question 5. A car moves with a speed of 40 km/h for 15 minutes and then with a speed of 60 km/h for the next 15 minutes. Find the total distance covered by the car.
Answer
Distance covered by the car with a speed of 40 km/h in 15 minutes = Speed × Time
= 10 km
Distance covered by the car with a speed of 40 km/h in 15 minutes = Speed × Time
= 15 km
Total distance covered by the car = (10 + 15) km = 25 km
Question 6. A simple pendulum takes 15 seconds to complete 5 oscillations. What is the time period of pendulum?
Answer
The time taken by pendulum to complete 1 oscillation is called time period
The time taken by pendulum to complete 5 oscillation = 15 sec
The time taken by pendulum to complete 1 oscillation = 15/5= 3 sec
So time period = 3 sec