[**NCERT In Text**]

A farmer moves along the boundary of a square field of side 10 m in 40 s. What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds from his initial position?

Given, Side of the square field= 10m

Therefore, perimeter = 10 m x 4 = 40 m

Farmer moves along the boundary in 40s.

Displacement after 2 m 20 s = 2 x 60 s + 20 s = 140 s =?

Since in 40 s farmer moves 40 m

Therefore, in 1s distance covered by farmer = 40 / 40 m = 1m

Therefore, in 140s distance covered by farmer = 1 X 140 m = 140 m

Now, number of rotation to cover 140 along the boundary= Total Distance /
Perimeter

= 140 m / 40 m = 3.5 round

Thus, after 3.5 round farmer will at point C of the field.

Thus, after 2 min 20 seconds the displacement of farmer will be equal to 14.14 m
north east from initial position.

Which of the following is true for displacement?

(a) It cannot be zero.

(b) Its magnitude is greater than the distance travelled by the object.

Answer

None of the statement is true for displacement First statement is false because displacement can be zero. Second statement is also false because displacement is less than or equal to the distance travelled by the object.

Speed |
Velocity |

Speed is the distance travelled by an object in a given interval of time. | Velocity is the displacement of an object in a given interval of time. |

Speed = distance / time | Velocity = displacement / time |

Speed is scalar quantity i.e. it has only magnitude. | Velocity is vector quantity i.e. it has both magnitude as well as direction. |

[**NCERT In Text**]

Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?

The magnitude of average velocity of an object is equal to its average speed, only when an object is moving in a straight line.