- #1

jemerlia

- 28

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## Homework Statement

A rock is thrown upwards at an angle of 35.0° to the horizontal. The

rock hits a signpost 15.0 m away at a point 2.00 m above the level

from which it was thrown.

Calculate the initial velocity of the rock.

## Homework Equations

d = v * t

d= displacement, v=velocity, t=time

x=x0+v0t+1/2gt^2

x= displacement at t

x0 = initial position

v0 = initial velocity

t=time

## The Attempt at a Solution

It appears that the x displacement is related:

(1) 15=Vx0 x t

(vx0 is the initial x-component velocity)

because the x velocity is unchanged

The y velocity is related:

(2) 2=vy0t +1/2gt^2

where vy is the initial y vector component

Also:

(3) vx = v0 cos 35

(4) vy = v0 sin 35

It appears possible to substitute for vx, vy so that

15= v0 x cos 35 x t

2= v0 x sin 35 x t + 1/2 gt^2

They look like simultaneous equations but I do not obtain the expected result :(

Help and advice gratefully received.