What is the acceleration at zero speed

Movements with constant acceleration

The braking formula¶

For braking in particular, there is another useful formula that can be derived from equation (4) above. [3] At an initial speed applies to the relationship between , and :

This equation is often called the “braking formula”; in the case can be used to reduce the braking distance calculate immediately if the initial speed and acceleration are known. The “braking formula” can, however, also be used in general for movements with constant acceleration and, in particular, makes arithmetic easier if the task does not contain a time specification.

Response time and stopping distance

In order to calculate the total distance a vehicle needs to stop, the distance that the driver covers during the reaction time must be taken into account in addition to the braking distance. So the following applies:

During the reaction time, which is often simply assumed to be a “moment of shock”, the vehicle moves at constant speed further. It thus results with :

The braking distance (and thus also the stopping distance) increases with the square of the speed at the same braking acceleration; For this reason, speed limits are important for road safety in built-up areas and in places that are difficult to see.

Accelerations and forces

Accelerations generally occur when there is a resultant force acts on an object; applies to the acceleration , in which stands for the mass of the object. If one knows the forces acting on an object, then its motion can also be predicted using the above formulas; conversely, the corresponding forces can also be estimated from calculated or measured acceleration values.