[填空题]
A ball of mass 1.6 kg is tj;er4 f wf8h(u7wcf()pryan(0 rtl;dropped from a very9wo xi5 qt9t5h high building. The only forces acting on the ball are the force of gravity and air resistance. The graphqo5 9twixt9h5 shows the variation of the vertical velocity v of the ball with time t.
1.(1)Define terminal speed.
(2)State the terminal speed of the ball.
2.Estimate the vertical displacement of the ball during the 10.0 s of motion.
3.(1)Calculate the instantaneous acceleration of the ball at t= 2.0 s.
(2)Determine the magnitude of the vertical component of air resistance at t=2.0 s. $F_d$ = N
