Braking delay

The braking deceleration , also negative acceleration , indicates how much a body is braked. The braking deceleration is given in the unit m / s².

The mean braking deceleration  a of braking from speed  v to zero with braking distance  s is:

${\ displaystyle a = - {\ frac {v ^ {2}} {2s}}}$

The mean deceleration of braking from speed  v 2 to speed  v 1 with braking distance  s is:

${\ displaystyle a = - {\ frac {1} {s}} {\ biggl (} {\ frac {v_ {2} ^ {2}} {2}} - {\ frac {v_ {1} ^ {2 }} {2}} {\ biggr)}}$

Example: starting speed v 2 = 20 m / s, remaining speed v 1 = 10 m / s, braking distance s = 100 m:

${\ displaystyle a = {\ frac {(20 \, \ mathrm {m / s}) ^ {2} - (10 \, \ mathrm {m / s}) ^ {2}} {2 \ cdot 100 \, \ mathrm {m}}} = 1 {,} 5 \, \ mathrm {m / s} ^ {2}}$

The braking delay is z. Sometimes also given in fractions or multiples of the acceleration due to gravity . ${\ displaystyle g}$

meaning

The braking deceleration is an important criterion for the safety of vehicles and ships and should be as high as possible. When spacecraft re- enters, however, it must not exceed certain values ​​depending on the payload and thermal load.

literature

• Heinz Burg, Andreas Moser (ed.): Handbook of traffic accident reconstruction. Accident recording - vehicle dynamics - simulation, 3rd edition, Springer Verlag, Berlin / Heidelberg 2017, ISBN 978-3-658-16142-2 .
• Horst Bauer: Driving safety systems. 2nd edition, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig 1998, ISBN 978-3-322-91815-4 .
• Diedrich Lütjen, Manfred Müller: Automobile computing. BG Teubner Verlag, Stuttgart 1984, ISBN 978-3-519-06721-4 .