An object moving in a circular orbit at a constant speed has a changing velocity. This is because velocity is a vector quantity that depends on speed and direction. The object in orbit is ...

It is not only moving objects whose speed can vary. The speed of the wind and the speed of sound also vary. A typical value for the speed of sound in air is about 330 m/s.

Motion in a plane. Cases of uniform velocity and uniform acceleration-projectile motion. Uniform circular motion. Intuitive concept of force. Inertia. Newton's first law of motion; momentum and ...