Class 7 Science Chapter 13 |Time and motion class 7 Easy Notes

Class 7 Science Chapter 13 Time and motion Question answers is important for the students of 7th standard. Notes are provided here in such a way that students can understand the Chapter in an interesting way. This Class 7 Science Chapter 13 Time and motion Question answers could provide extra benefits in excelling a students curriculum . Students should practice their solutions regularly to prepare effectively for their examination.

1. Tick the correct option to complete its sentence

1. An aircraft flying at a constant speed is an example of…

a) Periodic motion

b) Random motion

c) Uniform motion ✔

d) Non- uniform motion

2. The hour hand of a watch is an example of…

a) Uniform motion ✔

b) Rectilinear motion

c) Random motion

d) Periodic motion

3. If we measure the distance in kilometres and the time in hours, the unit of speed is written as …

a) h/kms

b) k/second

c) km/h ✔

d) kmh

4. If an object is travelling with uniform motion, it’s speed is equal to the. ..

a) Total time taken

b) Total distance covered

c) Distance travelled ÷ time taken ✔

d) Time taken in the first half of it’s motion

5. If a distance- time graph of an object in motion is not a straight line, the object is…

a) Stationary

b) In uniform motion

c) In non – uniform motion ✔

d) In rectilinear motion

6. 20 hours is…

a) 2 p. m.

b) 8 p. m. ✔

c) 8 a. m.

d) 12 a. m.

Answer the following questions in one sentence.

1. What are obelisks?

Ans : Obelisks were tall four- sided curved pillars constructed by Egyptian kings more than 5000 years ago.

2. Define an oscillation.

Ans: One complete movement of a pendulum is called an oscillation.

3. Where is quartz found?

Ans: Quartz is a mineral found in the Earth’s crust .

4. What are the two methods of writing time in a day?

Ans: One of the methods is known as the 12- hour method and the other method is known as the 24- hour method.

5. Name the SI unit of time.

Ans: Second (s) is the SI unit of time.

6. What is motion?

Ans: When an object changes it’s position with time, it is called motion.

7. List the types of motion.

Ans: The two different types of motion are – Uniform motion and Non-uniform motion

8.What does a speedometer measure?

Ans: A speedometer records the speed of a vehicle in motion.

Answer the following questions in two sentences.

1. How is speed calculated? Write the formula.

Ans: Speed is calculated by dividing total distance travelled by time taken to cover the distance. Speed of an object = Total distance travelled/time taken to cover the distance OR, S = D/T

2. What is an atomic clock?

Ans : An atomic clock is a type of clock used to measure the accurate standard time of our nation. It can measure time intervals with an accuracy of one-millionth of a second and works on radiation emitted by cesium atoms.

3.What does the speed of an object in motion depend on?

Ans: The speed of an object in motion depends on two factors : a) The total distance travelled b) The total time taken to travel the distance.

4.Explain the function of an odometer.

Ans: An odometer is a tool for tracking the distance a car, motorcycle, or other type of vehicle has travelled. It is also used by people who construct roads and survey land.

5.Differentiate between uniform and non- uniform motion.

Ans : An object moving in a straight line at a constant speed is said to be in uniform motion. – When moving uniformly, an object travels the same distance in the same amount of time. – During uniform motion, the object’s velocity (speed in a certain direction) stays constant. – An automobile travelling at a constant 60 kph down a straight highway serves as an example of uniform motion.

Non-uniform motion is defined as when an object does not travel in a straight path at a constant speed. – The item may change its speed, direction, or both during non-uniform motion. – During non-uniform motion, the object travels unequal distances at intervals of time. – A ball rolling down a hill or an automobile accelerating or decelerating are examples of non-uniform motion.

Answer the following questions in about four – five sentences.

1. Explain how a quartz watch works.

Ans : A tiny quartz crystal in the form of a bar is used by the electrical circuit of a quartz watch to power it. The crystal is controlled by an electrical cell in the watch, which keeps it vibrating regularly at a specific frequency. A tiny computer chip then converts these vibrations into electrical pulses. These pulses then drive a tiny motor, which in turn moves a series of gears that move the watch’s hands. In effect, the quartz crystal’s vibrations act as the watch’s heartbeat, controlling the precision of the timekeeping

2. Differentiate between a speedometer and an odometer.

Ans: A speedometer gives the driver real-time information by measuring and displaying the current speed of a vehicle, often in miles per hour (mph) or kilometres per hour (km/h). On the other hand, an odometer records the overall mileage a vehicle has logged over its life. It keeps track of and shows the total mileage since the car was made or the last time the odometer was reset, frequently in miles or kilometres.

3. Describe a periodic motion with an example.

Ans: Periodic motion could be defined as a repetitive and predictable motion that occurs over a fixed interval of time. An example of periodic motion is the swinging of a pendulum. As a pendulum swings back and forth, it repeats its motion with a constant period, meaning it takes the same amount of time to complete each cycle.

4. Describe the 2 methods of noting time.

Ans : There are two primary ways to keep track of time:

Twelve-hour clock – The day is split into two 12-hour halves using this approach, which are referred to as AM (ante meridiem, before noon), and PM (post meridiem, after noon). After 12 PM, the clock starts afresh at 1, and the hours are numbered from 1 to 12. 7:30 AM and 7:30 PM, for instance, denote two different times.

Military time, commonly referred to as the 24-hour clock, is a time representation method that uses a 24-hour format. By employing a continuous count of the hours from 00:00 (midnight) to 23:59 (11:59 PM), it does away with the distinction between AM and PM. For instance, 07:30 corresponds to 7:30 AM and 19:30 corresponds to 7:30 PM.