The relative speed of two objects is the vector sum of their speeds. The formula that calculates it also considers their masses and the displacement vector between them. Calculating relative speed is necessary for calculating the momentum of an object and its direction in a multi-body system. The formula that calculates the speed of an object divided by t (t is equal to the time elapsed since some initial frame), called the rate of change of speed, is based on Newton’s second law. This is the fundamental equation for calculating relative speed. Relative speed helps you understand how far something has travelled in a given amount of time.
The relative speed of two objects is their speed divided by the mass of one object. An object with a greater relative speed can exert more momentum on another object. It is very useful for calculating the final direction of one moving body if it collides with another stationary or moving body.
The relative speed formula requires an acceleration relation between the objects and an initial speed of each object (assuming zero initial displacements).
The acceleration relation between the two objects can come from any force relations or potential relations that exist between them, such as gravitational potential or Coulomb’s law.
Accuracy: This equation does not require acceleration relations between the objects. It is more accurate than equations that do require them. Even without an acceleration relation, this equation is still the most accurate formula for calculating the relative speed of two objects.
Term: The number of terms in the vector sum can be determined by using this formula and dividing it by time. The first term is the normalised total mass of both objects. The second is the acceleration of each object. The last term is the acceleration of one object divided by its mass. This means that if one object increases or decreases its speed while another object remains constant, relative speed will increase or decrease, respectively.
Acceleration: Acceleration is directly related to speed. When one object accelerates towards another object, the relative speed of both objects increases if we divide it by the mass of one object, this is why large objects have very low relative speeds.
Distance and time are inversely related. If one object decreases its speed by dividing by a smaller number, the distance between them will increase. If the object increases its speed by dividing by a larger number, the distance between them will decrease.
When two objects are moving, there is a relative speed between them. This is because both of their speeds are changing all the time. The relative speed can be calculated by adding the speeds of one object to that of another. If one object remains constant while the other moves, there will be a speed difference between them; this will result in a final relative speed different from the sum of initial speeds.
We can understand the relative speed formula by understanding the relationship between speed, time, and distance.
Suppose that one object has a speed of 150 m/s while another object has a velocity of -50 m/s. If both objects move at the same speed of 150 m/s, their relative speeds are still 50 m/s, but their total mass differs. Their speeds are all different because their masses are different. If one object accelerates or decelerates, the relative speed between the two objects changes. Because this only applies to non-zero displacements of both objects, it is more accurate than previous equations for calculating relative speed.
Relative speed has many applications in solving day-to-day problems.
The relative speed of two objects is how fast one object is moving with respect to another. Relative speed can be positive, meaning the first object is going in the same direction as the second, or negative, meaning the first object is going in a different direction from the second.
The relative speed formula uses symbols that you might find on your calculator: “>” means ‘is greater than, “<” means ‘is less than, and “=” means ‘equals.’ If the notation uses the plus sign, meaning that the first object (the one doing the moving) is going in a direction to which it is pointing.