Tuesday , May 26 2020 # NCERT 7th Class (CBSE) Science: Time and Motion

#### Question: Graphic represent the nature of the distance-time graph of motion of the given object –

Answer: (1) An athlete running at a constant speed. (2) A train waiting at a station for another train pass by. #### Question: Differentiate between periodic and non periodic motion.

Answer: Differentiate between periodic and non periodic motion are:

Periodic motion
Non periodic motion
1. In periodic motion the object always comes after a time period.
1. In non periodic motion object does not always comes after a time period.
2. For Eg-pendulum of a clock, Revolution and Rotation of the earth.
2. For Eg- Time taken to go to school.

#### Question: Define speed Mention SI unit of speed.

Answer: The distance covered by a body in unit time is called speed. Usually speed is denoted as km/h, but the SI unit of speed is metre per second (m/s). The unit of speed can be converted in km/h, m/h.

#### Question: The length of the simple pendulum is increased? What will happen to time period?

Answer: If the length of the simple pendulum is increased the oscillations will a slow down.

#### Question: The mass of the bob is doubled? What will happen to timeperiod?

Answer: The time will remain unchanged.

## NCERT 8th Class CBSE Science: Friction

Friction: 8th Class NCERT CBSE Science Chapter 12 Question: What is friction? Answer: Friction is a …