[问答题]
If air resistance is negs5ogx cic1 9n6lrfeo )iq d q(pa6pn6-(ected, show (algebraically) that a ball thrown vertically upwara6i-n(rqefpo6 dq ( )pd with a speed $v_0$ will have the same speed, $v_0$, when it comes back down to the starting point.
