4ESO Física i Química : ARTICLE 118 : FREE FALL MOTION exercises.

    -  Watch the following video and later we will do a similar exercise all together :

       

   Accelerated dropping motion exercise.

-  Watch the previous video and the next ones you find below and try to do the following two exercises at home :  (you still have the videos with the solution in case you don’t know how to finish them).

1-    Problem 1 :

        a) A child throws just upright to the sky a little stone with a starting velocity of 6 m/s.  Find the time the Stone takes to reach the higher position.

        b) After that, work out the distance this stone goes over when it finally hits the ground at the end of its movement. How long does the Stone take to arrive again to the ground from its higher position on the top?.

        c) Work out the total displacement the stone does from the beginning to the end of its movement and the total time of this movement from the beginning to the end.

                         VIDEO 1 WITH THE PROBLEM’S SOLUTION.

2- Problem 2 :

    From the top of a skyscraper a stone is thrown in a straight line motion to the ground with a starting velocity of 2 m/s. if the stone takes 5 seconds to hit the ground, work out how high the skyscraper is.

                         VIDEO 2 WITH THE PROBLEM’S SOLUTION.

 (There is a mistake at the video because , as the Stone goes down some direction to gravity,  the starting velocity must have same sign as gravity, if I write minus sing for gravity I must write also minus sign for starting velocity.

   I should have written  - v₀  instead of + v₀ for the starting velocity. 

   So It must be written  :       0 = h - v₀.t - 1/2.g.t²     ).

               Then the skyscraper’s high is :  h = 10 + 122’5 = 132’5 m

    Once you have tried to do these exercises and watched the videos, will you do a few more similar exercises next Friday in class. Then it is important you do at home the suggested activities on this article 118.

 DON’T FORGET TO DO THIS AT HOME!!!

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   - Now that you have watched all these videos and last friday you have also tried a few more similar exercises in class, try now a few more ones like that at home as homework :

   Do exercises 43, 27, 58 and 59 from your book and have them ready on Monday.