a.
• $W_{A}$ = $Wđ_{A}$ + $Wt_{A}$
<=> $W_{A}$ = $\dfrac{1}{2}$m$v_{A}^2$ + mg$z_{A}$
<=> $W_{A}$ = $\dfrac{1}{2}$.0,05.$6^2$ + 0,05.10.2
=> $W_{A}$ = 1,9 (J)
• $W_{A}$ = $W_{max}$
<=> 1,9 = mg$z_{max}$
<=> 1,9 = 0,05.10.$z_{max}$
=> $z_{max}$ = 3,8 (m)
b.
$W_{A}$ = $W_{B}$ = $Wt_{B}$ + $\dfrac{1}{2}$$Wt_{B}$
<=> 1,9 = $\dfrac{3}{2}$mg$z_{B}$
<=> 1,9 = $\dfrac{3}{2}$.0,05.10.$z_{B}$
=> $z_{B}$ = $\dfrac{38}{15}$ (m)
c.
$W_{A}$ = $W_{C}$ = $Wđ_{C}$ + $Wt_{C}$
<=> 1,9 = $\dfrac{1}{2}$m$v_{C}^2$ + mg$z_{C}$
<=> 1,9 = $\dfrac{1}{2}$.0,05.$3^2$ + 0,05.10.$z_{C}$
=> $z_{C}$ = 3,35 (m)