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 is a force that opposes motion and wastes energy. Some of the energy used to create the forces that move objects is also used to overcome oppositional forces due to friction. Friction reduces the efficiency of machines and mechanisms, and good designers are always looking for ways to minimize friction.