1. a car speeds up from 10.0 m/s to 45.0 m/s in 4.0 s. what is its acceleration? in your response, show your work, the given and unknown quantities, the equation, and any necessary algebra. express your answer with the correct number of significant digits.

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.