Problem 4 A particle is moving in the xy plane according to r-15m+(3 m/s) t']+[45 m-(1 m/s²)]j What are a) The particle's position and velocity at t-4 s? b) The particle direction of motion with respect to the X-axis at that time? c) The average acceleration between t-0 s and 1-4s? d) The instantaneous accelerations at t-0 and t-4s? Problem 5 Galileo standing on the leaning tower of Pisa as shown below, throws a rock from the top at an upward angle of 45° with speed vo. The rock is in flight for 4.0 s and hits the ground 20 m from the base of the building. Ignore air resistance, and ignore the fact that the tower tilts a bit. a) What is the speed vo? b) How high off the ground is the top of the tower? c) What is the speed of the rock just before it hits the ground? 20 m-