## Kumar Ketan is teaching live on Unacademy Plus

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18.2k views unacademy Kumar Ketan Educator since January 2018 #6 years teaching experience #IIT JEE Physics #YouTuber (140k+ subs) #Unacademy educator(16k+ lifetimeviews) #Under graduate topper Follow me on the Unacademy Learning App 1k Followers Following Courses Get updates about new courses Watch all my lessons .Download slides and watch offline All courses HINDI Relative Motion (Hindi) Kinematics: Relative Motion Rain Drop and Boat River Proble.. 5.0 (5 ratings) Kumar Ketan Kumar Ketan

CRAs4 Physics course for IIT JEE Kinematics & Dynamics 1D Non-Accelerated Motion 1D Accelerated Motion Force Frictional Force Newton's Law of Motion Relative Motion

FREE FALL A body falling under the action of gravity is known as freely falling body. The motion is known as free fall. Let us consider a body at height H. Two cases arise. (1) Body is dropped (u-0) (2) Body is thrown with some initial velocity

(a) When body is dropped u-0, a g then (1) v gt (2) v 2gh Ar

Surface

(b) When body is thrown downwards with some initial velocity Let the initial velocity be u, a - g, then (2)v2 - u2 +2gH (3)s - ut h gt2

Maximum height attained When the body will attain maximum height the velocity of the body will be zero. That is v-0, a g, s-H Using v2 -u2 2as, we get

Time of Flight (a)Time taken for upward motion Using v - u + at, we get Or t=u/g

(b) Time taken for downward motion Using v - u gt, we find Or u gt or t-u/g u.2)

From (1) and (2), we can conclude that Time of ascent = Time of descent Therefore, time of flight = 2u/g

A body is thrown with the speed of 12 m/s vertically upward from the ground. What will the vertical distance in last 0.4 sec before reaching 1.2 sec maximum hight? (a) 0.6 m (b) 0.8 m (c) 0.4 m (d) 0.2 m

We take u at 0.8 sec h=ut + gt2 = 4 x 0.4- 10 (0.4)2 1.6-5 (0.16) = 1.6-0.8 = 0.8 m

x=5 distance = 7x = 7 5 = 35

For one dimensional motion the angle betweern a and v is either 0 or 180 . And it does not change with time. . For two dimensional motion, the angle between a and v is other than 0 or 180 . Also it may change with time

.If the angle between a and v is 0 or 180 the path of the particle is a straight line. .If the angle between a and v is other than 0 or 180 , the path of the particle is a curve. . If the angle between a and v is 90%, the path of the particle is a circle.

. For motion with constant acceleration the graph between x and t is a parabola. e In the above case the graph between v and t is a straight line. . Also in the above case, the graph between v and x is a parabola.

Which of the following graphs represents the uniform motion ?

Which of the following distance time graphs represents one dimentional uniform motion?