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## Homework Statement

A train is travelling at 3.73 degree incline at a speed of 3.25 m/s, when the last car breaks free and begins to coast without friction.

(i) How long does it take for the last car to come to rest momentarily?

(ii) How far did the last car travel before (momentarily) coming to rest?

(iii)For a real train the friction between the car and the track can be described by a friction coefficient. Find this coefficient assuming that the time it takes for the car to come to rest is 3s.

## Homework Equations

v=u + at

v^2=u^2 + 2as

## The Attempt at a Solution

(i) u=3.25 m/s

v=0m/s

s= ?

t= looking for..

a=9.8sin3.25= -0.55 m/sec^2

t= v-u/a

t= 0-3.25 / -0.55 = 5.909 seconds

(ii) u=3.25 m/s

v=0m/s

s= looking for..

t= 5.909 seconds

a=9.8sin3.25= -0.55 m/sec^2

s= v^2 -u^2 / 2a

s= 0^2 - 3.25^2 / 2(-0.55) = 9.602 metres

I haven't a clue about the third part. can anyone help?