";s:4:"text";s:2969:" Hence, the car is considered to be undergoing an acceleration. Velocity is a physical vector quantity; both magnitude and direction are needed to define it. Their velocities are different even though their speeds are the same. Velocity is equivalent to a specification of an object's speed and direction of motion. Often these problems require calculating the relative motions of trains, planes and automobiles. The first shows the relationship of force, mass and acceleration. Velocity is a vector quantity that refers to \"the rate at which an object changes its position.\" Imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. Equations for speed, velocity and acceleration depend on change of position over time. Miles per hour (mi/hr or mph), kilometers per hour (km/hr or kph), feet per second (ft/s or ft/sec) and meters per second (m/s) all indicate speed.Average speed can be found using the total distance travelled, usually abbreviated as d, divided by the total time required to travel that distance, usually abbreviated as t. So, if a car takes 3 hours to travel a total distance of 150 miles, the average speed equals 150 miles divided by 3 hours, equals an average speed of 50 miles per hour (150 ÷ 3 = 50).Problems involving calculating speed, velocity and acceleration commonly appear in physics. The commonly used formula for speed calculates average speed rather than instantaneous speed. Many problems, however, assume that the object continues traveling in the same direction during that short interval of time. Karen taught middle school science for over two decades, earning her Master of Arts in Science Education (emphasis in 5-12 geosciences) along the way. Well, the difference between speed and velocity is that speed gives us an idea of how fast an object is moving whereas velocity not only tells us its speed but also tells us the direction the body is moving in. Check with the teacher.Karen earned her Bachelor of Science in geology. She worked as a geologist for ten years before returning to school to earn her multiple subject teaching credential.