A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling west at 20.0 m/s. The cars stick together. What is the speed of the wreckage just after the collision? Express your answer in term of m/s. Write done the number only. Keep two significant figures.

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.