It is also what it takes to slow things down or hold them together or split them apart. Speed, velocity and acceleration Velocity is sometimes confused with speed, but it is different.
Speed is said to be a scalar quantity.
Velocity, however, is a vector quantity. This means how fast the bike is moving in a particular direction. Acceleration, too, is a vector quantity. It is not just how quickly an object gains velocity, but the rate it gains velocity in a particular direction. When you throw a ball up in the air, the force of your throw gives it enough acceleration to move up against the force of gravity.