Answer:
(a) -472.305 J
(b) 1 m
Explanation:
(a)
Change in mechanical energy equals change in kinetic energy
Kinetic energy is given by[tex]0.5mv^{2}[/tex]
Initial kinetic energy is [tex]0.5\times 69\times 3.7^{2}=472.305 J[/tex]
Since he finally comes to rest, final kinetic energy is zero because the final velocity is zero
Change in kinetic energy is given by final kinetic energy- initial kinetic energy hence
0-472.305 J=-472.305 J
(b)
From fundamental kinematic equation
[tex]v^{2}=u^{2}+2as[/tex]
Where v and u are final and initial velocities respectively, a is acceleration, s is distance
Making s the subject we obtain
[tex]s=\frac {v^{2}-u^{2}}{-2a}[/tex] but a=\mu g hence
[tex]s=\frac {v^{2}-u^{2}}{-2\mu g}=\frac {0^{2}-3.7^{2}}{-2*0.7*9.81}=0.996796272\approx 1 m[/tex]
