A glass marble dropped from a certain height above the horizontal surface reaches the surface in time t and then continues to bounce up and down. The time in which the marble finally comes to rest is

tAB=2hg                tBC+tCB=22h1g=22e2hg=2e2hg tBD+tDB=2e22hg ∴  Total time taken by the body in coming to rest=2hg+2e2hg+2e22hg+.......... =2hg+2e2hg[1+e+e2+............] =2hg+2e2hg×11−e=2hg[1+e1−e]=t(1+e1−e)