Assume that the positive x-axis points east, and that the positive y-axis points north. a house is located at (0, 0), and a runner leaves the house at time t = 0. at a constant velocity, she runs roughly northeast until time t = 10 when she reaches the center of town, located at (4, 3). at this point, she changes direction and slows down, but continues jogging at a (different) constant velocity until time t = 19 when she reaches the library, located at (4, 6).
1. find parametric equations that describe the path of the runner from her house to the center of town. make sure the parameter t is varying with time as indicated.

Can someone explain to me how to do this problem ?

Askydiver weighing 140 lb (including equipment) falls vertically downward from an altitude of 19,000 ft and opens the parachute after 18 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.55|v| when the parachute is closed and is of magnitude 14|v| when the parachute is open, where the velocity v is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. (a) find the speed of the skydiver when the parachute opens. (b) find the distance fallen before the parachute opens. (c) what is the limiting velocity vl after the parachute opens? (d) determine how long the sky diver is in the air after the parachute opens. (e) plot the graph of velocity versus time from the beginning of the fall until the skydiver reaches the ground.

Suppose that 27 j of work is needed to stretch a spring from its natural length of 6 m to a length of 9 m. (a) how much work is needed to stretch the spring from 12 m to 14 m? j (b) how far beyond its natural length will a force of 78 n keep the spring stretched?