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## Homework Statement

I. A projectile is launched at an angle 'alpha' to the horizontal with an initial velocity u. Write down expressions for (1) horizontal velocity (2) total time of flight. Combine these expressions to show that R = (u^2 sin 2'alpha')/g.

II. Over a period of 5.0s a point changes its velocity from 10m/s at a bearing of 90 degrees to 10m/s at a bearing of 150 degrees.

Calculate:

(a) change of velocity

(b) the average acceleration

## Homework Equations

I. Equatons of motions??!!

II. v = rw

a = v/r^2

## The Attempt at a Solution

I. I got the first one, Ux = u cos 'alpha'. I cannot find an appropriate equation for solving for time. This is blocking the whole problem for me.

II. change in velocity should be zero