total acceleration

[runner1738]

at the moment the train's speed is 54 km/h. what is the magnitude of the total acceleration? units m/s^2 r=173 and it takes 18.9 s to slow down from 82 km/h to 37 km/h, the a tangential is .6614 so is it (15)^2/173 + .6614 = total?

[Andrew Mason]

at the moment the train's speed is 54 km/h. what is the magnitude of the total acceleration? units m/s^2 r=173 and it takes 18.9 s to slow down from 82 km/h to 37 km/h, the a tangential is .6614 so is it (15)^2/173 + .6614 = total?From your question it appears that we have a train on a curved track with radius 173 m. and slowing down at the rate of 12.5 m/sec in 18.9 seconds. You want to know its total acceleration when its speed is 54 km/hr (15 m/s).

In order to work this out, you have to add them as vectors. The accelerations are perpendicular to each other. So:

a_l^2 + a_c^2 = a_{total}^2

AM