#"Object has a kinetic energy : "E_k=1/2*m*v^2# #E_k:"The kinetic energy of object"# #m:"mass of object"# #v:" velocity of object"# #"The kinetic energy of object is turned to the heat energy by "# #"the friction force."# #E_k=F_f*Delta x# #1/2*cancel(m)*v^2=u_k*cancel(m)*g*Delta x# #Delta x=v^2/(2*u_k*g)#