Ask Question
24 October, 19:37

a force of 9.0N is applied to a body at rest on a smooth horizontal surface. if the body has a mass of 18.0Kg and it moves in the direction of the force, find the workdone in (a) the first four seconds. (b) the fourth second

+1
Answers (1)
  1. 24 October, 20:01
    0
    (a) 36 J (b) 15.75 J

    Explanation:

    In this case a body of 18 kg is placed on the smooth surface.

    The distance covered covered by the body in four seconds can be found by the relation S = u t + 1/2 a t²

    Here S is the displacement, u is the initial velocity and a is the acceleration of the body. t is the time taken

    In this case initial velocity u = 0, because the body is at rest.

    the acceleration is force/mass = 9/18 = 0.5 m/sec²

    The values are substituted in the above equation

    Thus S = 0 + 1/2 x 0.5 x (4) ² = 4 m

    Therefore the body will move 4 m in four seconds

    The work done = Force x displacement

    = 9 x 4 = 36 J

    The displacement in fourth second can be found by relation

    S₄ = u + a/2 (2 n - 1); where n is the number of seconds, which is 4 in this case

    Thus S₄ = 0 + 0.5/2 (2 x 4 - 1) = 3.5/2 = 1.75 m

    Therefore the work done = 9 x 1.75 = 15.75 J
Know the Answer?
Not Sure About the Answer?
Find an answer to your question 👍 “a force of 9.0N is applied to a body at rest on a smooth horizontal surface. if the body has a mass of 18.0Kg and it moves in the direction ...” in 📗 Physics if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers