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## Homework Statement

A train is moving counter-clockwise with a constant speed of 10 m/s in a circle of radius ##\frac {16} π## m. The plane of the circle lies in the x-y plane. At time

*t*= 0, the train is at P, when a stone is thrown from it with a speed of 10 m/s relative to the train towards the negative ##x## axis at an angle of 37° with the vertical ##z## axis (assume

*g*= 10 m/s

^{2}and sin 37° = ##\frac 3 5##). Find:

(a) the velocity of the stone relative to the train at the highest point of its trajectory.

(b) the co-ordinates of the point where it finally falls.

(c) the co-ordinates of the point at the highest point of its trajectory.

## Homework Equations

Let

**v**be the velocity vector of the stone relative to the train.

_{ST}**v**=

_{ST}**u**-

_{ST}*gt*##\hat k##

Also, position vector

**r = u**

_{S}*t - gt*##\hat k##

^{2}## The Attempt at a Solution

I know how to solve this problem, but there's just one hitch. The ##x## components of the velocity and co-ordinates they've given as the answer isn't matching with mine. Their answers are:

(a) (-6##\hat i## + 10##\hat j##) m/s

(b) (-4.5 m, 16 m, 0)

(c) (0.3 m, 8 m, 3.2 m)

Later, I found out that they haven't considered the centripetal acceleration (along the negative ##x## direction) that would be imparted to the stone at the instant of projection; due to the circular motion of the train. Why?