Answer:
W(fric) = -12000 J
Explanation:
Given that
mass ,m= 80 kg
Initial speed ,u= 0 m/s
Height ,h= 15 m
Final speed ,v= 0 m/s
We know that
Work done by all the forces = Change in the kinetic energy
[tex]W_{gravity}+W_{fric}=\dfrac{1}{2}mv^2-\dfrac{1}{2}mu^2[/tex]
[tex]W_{gravity}+W_{fric}=\dfrac{1}{2}m\times 0^2-\dfrac{1}{2}m\times 0^2[/tex]
[tex]W_{gravity}+W_{fric}=0[/tex]
W(fric)= - m g h
W(fric) = - 80 x 10 x 15 ( g=10 m/s²)
W(fric) = -12000 J
negative sign indicates that force and displacement is in opposite direction.
