Measurement of Time and Motion Class 7 Extra Questions and Answers Science Chapter 8

By tackling these Class 7 Science Extra Questions and Class 7 Curiosity Chapter 8 Extra Question Answer Measurement of Time and Motion, students will build a solid foundation in the topic.

Class 7 Science Chapter 8 Measurement of Time and Motion Extra Questions

Class 7 Science Chapter 8 Extra Questions on Measurement of Time and Motion

Measurement of Time and Motion Class 7 Very Short Question Answer

Question 1.
What is the SI unit of time?
Answer:
SI unit of time is second.

Question 2.
In which principle sun-dial is based?
Answer:
This is based on position of shadow formed by sun rays.

Question 3.
Who first mentioned Ghatika-yantra?
Answer:
Aryabhatta

Question 4.
How does an hourglass work?
Answer:
On the basis of flow of sand from one to another bulb.

Question 5.
How time is calculated in candle-clock?
Answer:
Bvmelting of wax till the marks, time was calculated.

Question 6.
Who invented pendulum clock?
Answer:
Christiaan Huygens in 1656.

Question 7.
What Galileo discovered about pendulum?
Answer:
The time period of pendulum of equal length is constant.

Question 8.
What is measured by speedometer?
Answer:
It measures speed of the vehicle.

Question 9.
What is measured by odometer?
Answer:
It measures total distance covered by the vehicle.

Question 10.
What is the formula to know average speed?
Answer:
Average speed = Total distance ÷ Total time

Question 11.
Which natural tool was used by Galileo to measure time?
Answer:
His pulse

Question 12.
Which clock timing is assumed accurate?
Answer:
Atomic clock

Measurement of Time and Motion Class 7 Short Question Answer

Question 1.
Write the difference between Sundial and water clock.
Answer:
Sundial is based on shadow formed by sun rays, and only works in day-time whereas water clock is based on flow of water, it works in day and night both.

Question 2.
Explain working-principle of Hourglass.
Answer:
There are two glass bulb in it. Sand flows slowly from upper bulb to lower bulb within a fixed timing. This time is measured.

Question 3.
Why pendulum clock is important?
Answer:
Pendulum clock made time keeping regular and accurate. It helped to measure time in minutes and seconds and helped in scientific discoveries.

Question 4.
What is uniform motion? Give example.
Answer:
When an object covers equal distance in equal time intervals, known as uniform motion. Ex. : A car moving on highway with uniform speed.

Question 5.
What is non-uniform motion? Give example.
Answer:
When an object covers different distances in equal time intervals, known as non-uniform motion. Ex. : A car moving in city traffic.

Question 6.
Differentiate between speedometer and odometer.
Answer:
Speedometer measures speed of a vehicle whereas odometer measures total distance covered by a vehicle.

Question 7.
Define average speed.
Answer:
Total distance covered is divided by total time taken to measure average speed or it can be said that average speed is the ratio of total distance and total time.

Question 8.
Where does non-uniform motion can be seen in daily life?
Answer:
Driving car in overcrowded roads, pedestrians, cycling etc. are the examples of nonuniform motion.

Measurement of Time and Motion Class 7 Long Question Answer

Question 1.
Give details about methods of time keeping in ancient times.
Answer:
People use natural events to measure time in ancient times Ex.: Sunrise, sunset, phases of the moon. Later sundial, hourglass, water clocks and candle clocks are used for this. These instruments measure time in minutes and hours.

Question 2.
Explain the experiment done by Galileo on pendulum.
Answer:
Galileo observed a suspended lamp on ceiling of the church which was swinging back and forth. He used his pulse to measure time, and found that the lamp took same time for each swing. After experimenting with different pendulum. He concluded that the time taken to complete one oscillation was always the same for a pendulum of given length.

Question 3.
Explain working-process of pendulum clock.
Answer:
Pendulum consists of a simple ball. When the ball released one’ side, it moves on the path repeatedly in a fixed time intervals. The time period of pendulum depends on its length. Time in pendulum clock is measured by this principle.

Question 4.
Explain co-relation between speed, distance and time.
Answer:
Speed, distance and time are co-related with each other. If the distance travelled and time taken by an object are known to us. Then the speed of the object can be calculated; and if distance and speed are known then the time can be calculated. Similarly, if speed and time taken are known then the distance covered by an object can be calculated.

Question 5.
A car travelled 150 meters in 10 seconds. Calculate its speed in km/h.
Answer:
Speed = [/latex]\frac{\text { Distance }}{\text { Speed }}[/latex]
= [/latex]\frac{\text { 150 }}{\text { 10 }}[/latex] = 15 m/s
To change m/s into km/s
⇒ 15 × \(\frac{(18)}{5}\) = 54 km/h
So the speed of car is 54 km/h.

Question 6.
A train running with a speed of 90 km/h. How much time it will take to cover the distance of 360 km?
Answer:
Time = [/latex]\frac{\text { Distance }}{\text { Speed }}[/latex]
= \( \frac{360}{90}\) = 4 hours
So, train will take 4 hours to cover the distance of 360 km.

Question 7.
A bus travels with the speed of 50 km/h. If it takes 2 hours to reach the city, then how far is the city?
Answer:
Distance = Speed × time
⇒ 50 × 2 = 100 km
So, the city is situated at the distance of 100 km.

Question 8.
Which instruments are used for time keeping in ancient time? Describe any one with diagram.
Answer:
In ancient time, many natural events (like sunrise, sunset, phases of moon) and mechanical instruments are used to measure time. Main instruments are:

1. Sundial
2. Water clock
3. Hourglass (Sand clock)
4. Candle clock

Description of water clock:
The water clock used the flow of water out or in a vessel to measure time. In one type, water flowed out from a vessel which had markings for time.

In other type, there would be a bowl, with a fine hole at the bottom, which was floated on the surface of water. It gradually filled up in a fixed time and finally sank. Then it was lifted and floated again.

Question 9.
What is simple pendulum? Which factors affect its time period? Explain in details.
Answer:
A simple pendulum consists of a small metallic ball (bob) suspended from a rigid support by long thread.
When the bob of the pendulum is moved slightly in one side and released, it starts oscillatory motion. Time period is time which is taken by the pendulum to complete one oscillation.

Factors affecting time period of pendulum : Length of pendulum: Time period increases when length increases.
Gravity : Change in distance with gravity also changes the time period of pendulum.

Mass of the bob: It doesn’t affect the time period. This property is used in clocks to measure time.

Question 10.
Differentiate between uniform and non-uniform motion. Give one example of each.
Answer:

Uniform motion	Non-uniform motion
1. When any object moves to equal distance in equal time interval.	When any object moves to different distances in equal time intervals.
2. The rate of speed is constant.	The rate of speed changes.
Ex.: A car travelling on a straight road with constant speed.	Ex. : A car travelling in city traffic.