Heart rate: Normally heart rate responds to exercise or physiologic demand levels. Usually we don't see it go over 180-200 even with high levels of exercise. This level while tolerated by 'normals' may be dangerous in patients with heart disease or other forms of disease. In other words, one number doesn't fit all.
In physics, motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance (scalar), velocity, acceleration, time and speed. Motion of a body is observed by attaching a frame of r...
Friction: Friction, force that resists the sliding or rolling of one solid object over another. Frictional forces, such as the traction needed to walk without slipping, may be beneficial; but they also present a great measure of opposition to motion.