[填空题]
A 65-kg trampoline artist jumpsavl-mugs2.s79 nuj-;r,e em e q9 wx*e vetpu9 or z/gat2qj gk)j-ht-gx +i*8a7rtically upward from the top of a platform with a speed g)jtk -*8ax7/hro a-z9gtipj+gt 2uqof 5.0 m/s. ($\alpha)$ How fast is he going as he lands on the trampoline, 3.0 m below (Fig. 6-38)?$v_2$ $\approx$ m/s
(b) If the trampoline behaves like a spring with spring stiffness constant 6.2×10$^{4}$ N/m , how far does he depress it? $y_3$ = m
