A Stone of mass 20kg fall from a height 5m.what is the time take to reach the ground? 2 . The average kinetic energy of body(neglect energy loss and take gravity 10m/s2)​

2 Answer

  • Total time taken is 980seconds
  • Answer:

    a) t = 1second

    b) KE = 1000Joules


    According to equation of motion,

    S = ut+1/2at² where

    S is the distance or height of fall = 5m

    u = initial velocity = 0m/s²

    a = +g = acceleration due to gravity = 10m/s²

    Substituting the values in the formula to get the time we have,

    5 = 0+1/2(10)t²

    5 = 5t²

    t² = 1

    t = 1second

    Time taken by the stone to reach the ground is 1second

    b) Kinetic energy is the energy possessed by a body by virtue if its motion.

    KE = 1/2MV² where m is the mass of the body and v is the velocity.

    Given mass = 20kg

    To get the velocity, we will use the equation of motion,

    v = u + at

    v is the final velocity

    u is the initial velocity = 0m/s

    a = +g = 10m/s

    t = time = 1second

    v = 0+10(1)

    v = 10m/s

    KE = 1/2×20×10²

    KE = 10×100

    KE = 1,000Joules