## How exactly does a dynamicist define deceleration in this case?

Hey friends. I wanted to know how exactly would a dynamicist define deceleration of a car on a road with humps and dips. Actually I always thought that deceleration of car on the road will be the vector a (see the diagram), however, in a sample problem in my dynamics book, it the car's deceleration is taken as the vector a_t (see the diagram), but it is not explicitly mentioned to be the tangential component. So how do we differentiate between the two cases?
Attached Thumbnails

 PhysOrg.com science news on PhysOrg.com >> Leading 3-D printer firms to merge in $403M deal (Update)>> LA to give every student an iPad;$30M order>> CIA faulted for choosing Amazon over IBM on cloud contract
 First off, dynamicists usually speak in terms of acceleration, rather than deceleration. You question seems to revolve around whether the term refers to the tangential component or the total vector. Unless otherwise specified, I would usually assume that the total vector is implied, but anytime there seems to be confusion, the only option is to ask for clarification.
 I believe what you're saying is correct. Thanks!

 Tags deceleration, dynamics, motion

 Similar discussions for: How exactly does a dynamicist define deceleration in this case? Thread Forum Replies Linear & Abstract Algebra 1 General Math 6 Introductory Physics Homework 2