Rest and Motion : Rest and Motion A body is said to be at rest if it does not changes its position with respect to time
A body is said to be in motion if it changes its position with respect to time
Orgin : Orgin To describe the position of the object we need to specify a reference point called orgin
Distance : Distance The total path length covered by the body is called distance
It is measured in meter
It has only magnitude , no direction
Displacement : Displacement The shortest distance measured from the initial to the final position of an object is known as displacement.
It is measured in meter
It has both magnitude and direction
Problem 1 : Problem 1 A body travels a distance of 15m from A to B and then moves a distance of 20m at right angles to AB. Calculate the total distance travelled and displacement
Problem 2 : Problem 2 A farmer moves along the boundary of a square field of side 10m in 40 sec. What will be its magnitude of displacement of the farmer at the end of 2min 20 sec
problem3 : problem3 An object is moving in a circle of radius ‘r’ calculate the distance and displacement
When it completes half the circle
When it completes one full circle
Problem 5 : Problem 5 Ravi told his friend that his house is 1km towards south from the main post office. Express the distance and displacement moved by the friend from the post office when he arrives at Ravi’s house.
Uniform and Non uniform motion : Uniform and Non uniform motion If the object covers equal distance in equal intervals of time ,it is said to be in uniform motion
If the object covers unequal distances in equal intervals of time ,it is said to be in nonuniform motion
Speed : Speed The distance traveled by the object in unit time is called speed
It is measured in m/sec
It has magnitude only
Average speed : Average speed total distance
Average speed = ---------------------
total time taken
Problem : Problem An object travel 16m in 4s and then another 16m in 2 sec. What is the average speed of the object.
problem6 : problem6 A car travels 30km at a uniform speed of 40km/hr and next 30 km at a uniform speed of 20 km/hr. Find its average speed