P. 4629. An object is left to move along a horizontal surface, on which friction is not negligible. At one moment its kinetic energy is 900 J, and 2 s later it is only 400 J, while the object covers a distance of \(\displaystyle \ell\).
\(\displaystyle a)\) By what factor will the further distance until the object stops be greater than the distance \(\displaystyle \ell\)?
\(\displaystyle b)\) How long does it take to cover this distance?
Deadline expired on 12 May 2014.