Projectile Motion: Solving for Explosion Co-ordinates

[thushanthan]

Projectile motion...?

Homework Statement

An artillery shell is fired with an initial velocity of 300 m/s at 55 degrees above the horizontal. It explodes on mountainside 42 s after firing. If x is horizontal and y is vertical, find the (x,y) co-ordinates where shell explodes?

Homework Equations

The Attempt at a Solution

I used r_f=r_i+v_vt+1/2 at²

where r_i=0
v_i=300 m/s
a=-9.8
t=42-0=42s
and theta = 55 degrees ...

I want to know whether my way is correct ? If it is wrong please provide any suggestions... I don't need the full solution...

 

[Redbelly98]

For this problem, you need to treat the x and y motions separately.

For example, a=-9.8 m/s² is true for the y-component of motion, but for the x-component a=0.

Also, for the initial velocity you'll need to use some trig to get the x- and y-components, given that the 300 m/s is at 55°.

 

[thushanthan]

Thank you! I got it.

I used X=V_x0t and Y=V_y0t+1/2a_yt² equations.