which best describes the difference between speed and velocity? A) velocity is instantaneous ,B) speed is a vector quantity

Which accurately compares concave and convex lenses?

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.

Why is the use of carbon-14 limited