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

Students can keep Class 7 Science Extra Questions and Class 7th Curiosity Chapter 8 Measurement of Time and Motion Important Extra Question Answer handy for quick reference during exams.

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.
A simple pendulum is oscillating between two points A and B as shown in Figure. Is the motion of the bob uniform or non-uniform?
Img- 1
Answer:
Non-uniform motion as the object is changing its motion.

Question 2.
Name the physical quantity that helps to identify which object moves faster or slower.
Answer:
Speed

Question 3.
What is speed?
Answer:
The distance covered by an object in a unit time is called its speed.

Question 4.
How did our ancestors find out the time of the day?
Answer:
Our ancestors could tell the approximate time of the day by observing at shadows.

Question 5.
What is the basic unit of time?
Answer:
Second

Question 6.
What do you mean when you say that a car is moving with a speed of 50 kilometres per hour?
Answer:
It means that the car will cover 50 kilometres distance in one hour.

Question 7.
What are the most common devices used to measure time?
Answer:
Clocks or watches are the most commonly used time-measuring devices.

Question 8.
Give an example of periodic motion.
Answer:
A well-known example of periodic motion is the motion of a simple pendulum.

Question 9.
What is a bob?
Answer:
The metallic ball in simple pendulum is called bob.

Question 10.
What is the time period of a simple pendulum?
Answer:
The time taken by the pendulum to complete one oscillation is called its time period.

Question 11.
Name the devices used by our ancestors to measure the time before pendulum clocks.
Answer:
Sundials, water clocks, hourglass and candle clocks.

Question 12.
What is speedometer?
Answer:
The device which is used to record the speed directly in km/h in the vehicles is called speedometer.

Question 13.
What is simple pendulum?
Answer:
The simple device consists of a small metallic ball and a long thread is called simple pendulum.

Question 14.
What is the function of an odometer?
Answer:
Odometer is used to measure the distance travelled by the vehicle.

Question 15.
What is the common property of most of the clocks?
Answer:
Most clocks make use of some form of periodic motion.

Measurement of Time and Motion Class 7 Short Question Answer

Question 1.
A spaceship travels 36,000 km in one hour. Express its speed in km/s.
Answer:
1 h = 60 min
1 min = 60 s
lh = 3600 s
Distance = 36,000 km
Speed = 36000/3600 km/s
= 10 km/s

Question 2.
What do you mean by average speed?
Answer:
The total distance covered by an object divided by the total time taken is called average speed.
Average speed = Total distance covered/Total time taken

Question 3.
What is an oscillation?
Answer:
An oscillation is the movement of a pendulum from its one extreme position to the other extreme position and then back to the former position.

Question 4.
Explain how Galileo contributed to the development of clocks.
Answer:
Once Galileo was sitting in a church. He noticed that a lamp suspended from the ceiling with chain was moving slowly from one side to other. He was surprised to find that his pulse beat the same number of times during the interval in which the lamp completed one oscillation. He found that a pendulum of a given length takes always the same time to complete one oscillation. This observation led to the development of pendulum clocks and other watches.

Question 5.
On the basis of the following table, calculate the speed of the car between 9:00 AM to 10:00 AM time interval.
Table: Odometer reading at different times of the journey

Answer:
Initial time = 9.00 AM
Final time = 10:00 AM
Initial reading = 36580 km
Final reading = 36620 km
Total distance = 36620 – 36580 = 40 km
Total time taken = 9:00 AM – 10:00 AM = 1 h
We Know That
Speed = Total distance covered/Total time tahen
= 40 km/ 1h = 40 km/h

Measurement of Time and Motion Class 7 Long Question Answer

Question 1.
What is a simple pendulum? Explain how does it perform oscillatory motion.
Answer:
A simple pendulum consists of a small metallic ball or a piece of stone suspended from a rigid stand by a thread. The metallic ball is called bob of the pendulum.

When the bob of the pendulum is released after taking it slightly one side, it starts to move to and fro. The to-and-fro motion of a simple pendulum is an example of an oscillatory motion.

Question 2.
Explain uniform and non-uniform linear motion with daily life examples.
Answer:
Uniform linear motion: An object is said to be in uniform linear motion if it covers equal distances in equal intervals of time along a straight line. For example, a person walking on a straight at the same speed. Non-uniform linear motion: An object is said to be in non-uniform linear motion if it cover unequal distances in equal intervals of time along a straight line. For example, a car moving on a straight road with changing speed.

Question 3.
Ravi travels from his house to the market. On Monday, he takes an auto and covers 6 km in 20 minutes. On Tuesday, he rides his bicycle and covers the same distance in 40 minutes.
(i) What is his speed while going by auto in km/h?
Answer:
Given: Distance = 6 km Distance
(i) Speed = \(\frac{\text { Distance }}{\text { Time }}\)
Time = 20 minutes = 0.33 hours
Speed = \(\frac{6}{0.33}\) = 18.18 km/h

(ii) What is his cycling speed in m/s?
Answer:
Distance = 6 km = 6000 m,
Time = 40 minutes = 2400 seconds
Speed = \(\frac{6000}{2400}\) = 2.5 m/s

(iii) What is his average speed for both trips in km/h?
Answer:
Total distance = 6km + 6km – 12km
Total time taken – 0.33 hours + 0.66
hours = 0.99 hours
Average speed = \(\frac{12 \mathrm{~km}}{0.99 \text { hours }}\)
= 12.12 km/h

Question 4.
During a science experiment, a student sets up a simple pendulum in the lab. She observes that the pendulum completes 40 complete oscillations in 80 seconds.
(i) Calculate the time period of the pendulum.
(ii) If the number of oscillations is doubled, but the total time also becomes double, will the time period change? Explain.
Answer:
Given: Number of oscillations = 40,
Total time = 80 seconds
(i) Time period (T) =
T = \( \frac{80}{40}\) = 2 seconds

(ii) If the number of oscillations becomes 80 and total time becomes 160 seconds.
T = \(\frac{160}{80}\) = 2 seconds

So, the time period remains the same. This is because the time period depends on the length of the pendulum, not on how many oscillations we count.

Measurement of Time and Motion Class 7 Skill Based Questions

Question 1.
Draw a diagram of (a) wall clock (b) table clock (c) digital clock. On what principle do all clocks work?
Answer:

All of these clocks work on the principle of periodic motion.

Question 2.
Observe the following figures and identify them.

Answer:
(a) Sundial at Jantar Mantar, Rajasthan.
(b) Sand clock
(c) Water clock

Measurement of Time and Motion Class 7 Case Based Questions

1. The smallest time interval that can be measured with commonly available clocks and watches is one second. However, special clocks are available that can measure time intervals smaller than a second. Some of these can measure time intervals as small as one millionth or even one billionth of a second.

1. A micro-second is a very small time interval. Write its value in fraction of a second.
Answer:
One millionth of a second

2. Define time period.
Answer:
Time taken by the pendulum to complete one oscillation is called time period.

3. What is the basic unit of time?
Answer:
Second
OR
How we can measure the time period of a pendulum?
Answer:
We can measure it with the help of stop watch, wrist watch or a table clock.

Measurement of Time and Motion Class 7 Suggested Projects and Activities

1. Find your pulse and count the beats for 60 seconds. Now, do a physical activity like jumping jacks or running in place for 1 minute and check your pulse again. Compare your pulse rate before and after the exercise. Explain why your heart beats faster during exercise.

2. Make an hourglass using two plastic bottles and sand. Flip it and use a stopwatch to measure how long the sand takes to fall from one bottle to another. Try changing the amount of sand and observe how it affects the time.

Measurement of Time and Motion Extra Questions for Practice

Question 1.
If a cyclist moves along a straight road covers unequal distances in equal time intervals, the motion is
(a) uniform linear motion
(b) non-uniform linear motion
(c) periodic motion
(d) oscillatory motion.

Question 2.
Convert 54 km/h into m/s.
(a) 15 m/s
(b) 20 m/s
(c) 12 m/s
(d) 18m/s.

Question 3.
A vehicle is moving at a speed of 50 km/h. How much time will it take to cover a distance of 100 km?
(a) 4 hours
(b) 3 hours
(c) 2 hours
(d) 1 hour

Question 4.
Read the given statements and select the correct option.
Assertion (A): If two objects cover the same distance in different times, the one that takes more time has greater speed.
Reason (R): Speed increases as time taken increases for the same distance.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question 5.
Match the items in Column A to those in Column B:

(a) (i) – (r), (ii) – (q), (iii) – (s), (iv) – (P)
(b) (i) – (q), (ii) – (p), (iii) – (s), (iv) – (r)
(c) (i) – (r), (ii) – (p), (iii) – (s), (iv) – (q)
(d) (i) – (r), (ii) – (q), (iii) – (p), (iv) – (s)

Question 6.
In which unit is the distance measured by an odometer usually expressed?

Question 7.
Which ancient device used sand to measure time?

Question 8.
What type of motion does a pendulum exhibit?

Question 9.
What is a sundial?

Question 10.
What is the basic unit of speed?

Question 11.
Why can not sundials be used at night to measure time?

Question 12.
A car travels 60 km in 30 minutes. What is its speed in km/h?

Question 13.
What makes a train faster compared to a cycle?

Question 14.
If an object travels different distances in equal time intervals, how do we calculate speed?

Question 15.
What type of motion is shown by a person running at a uniform speed on a straight road? Explain.

Question 16.
How can we compare the speeds of two objects to determine which one is moving faster?

Question 17.
What is a water clock and how was it used to measure time in ancient times?

Question 18.
A car travels 100 km in the first 2 hours and then covers another 50 km in the next 1 hour. Calculate the average speed of the car’s for the entire journey.

Question 19.
What is meant by one oscillation of a simple pendulum? How is it measured?

Question 20.
Rohit and Mohit start walking at the same time. Rohit covers 2 km in 30 minutes and Mohit covers 1 km in 30 minutes. Calculate their speeds in km/h and identify who is walking faster.

Question 21.
A pendulum completes 30 oscillations in 60 seconds. Find its time period. If the mass of the bob increases but the length of the pendulum remains the same, what will be the new time period?

Question 22.
A bus travels 40 km in 1 hour and 20 minutes, whereas the same distance is covered by a car in 60 minutes. What is the ratio of the speed of the car to the bus?

Question 23.
Aanya goes from her home to school. On the first day, she walks 4 km in 50 minutes and on the next day, she goes by cycle and covers the same distance in 15 minutes.
(i) Find her walking speed in m/s.
(ii) Find her cycling speed in km/h.
(iii) What is her average speed through the entire trip?

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