Homework Help: Easy-acceleration with unit vectors

PEZenfuego · Sep 9, 2012

1. The problem statement, all variables and given/known data

r1=(0m)
r2=(2000i + 1000j)m
v1=(200j)m/s
v2=(200i-100j)m/s
2. Relevant equations
tantheta=vy/vx

v2^2=v1^2+2ax
v2=v1+at
x2=x1+v1t+1/2at^2

3. The attempt at a solution

Thank you for any help

Draco27 · Sep 9, 2012

So what do we have to find??

PEZenfuego · Sep 9, 2012

find the saucer's acceleration in unit vectors and in terms of magnitude and direction.

SammyS · Sep 9, 2012

PEZenfuego said: ↑

1. The problem statement, all variables and given/known data

View attachment 50618

r1=(0m)
r2=(2000i + 1000j)m
v1=(200j)m/s
v2=(200i-100j)m/s
2. Relevant equations
tantheta=vy/vx

v2^2=v1^2+2ax
v2=v1+at
x2=x1+v1t+1/2at^2

3. The attempt at a solution

View attachment 50617

Thank you for any help

Are those kinematic equations for components of vectors, or for vectors themselves?

PEZenfuego · Sep 9, 2012

SammyS said: ↑

Are those kinematic equations for components of vectors, or for vectors themselves?

If you click the first picture, you will have an understanding equal to mine. I'm sorry.

SammyS · Sep 10, 2012

PEZenfuego said: ↑

If you click the first picture, you will have an understanding equal to mine. I'm sorry.

Sorry for the slow response.

I should have been more direct with my earlier response.

The set of kinematic equations you have
(v2)²=(v1)²+2ax
(v2)=(v1)+at
x2=x1+(v1)t+1/2at²
are valid for each component of displacement, velocity, and acceleration.

So you have two such sets of kinematic equations:
(v2)_x² = (v1)_x² + 2a_xx
(v2)_x = (v1)_x + a_xt
x2 = x1 + (v1)_xt + 1/2a_xt²

(v2)_y² = (v1)_y² + 2a_yy
(v2)_y = (v1)_y + a_yt
y2 = y1 + (v1)_yt + 1/2a_yt²

PEZenfuego · Sep 10, 2012

SammyS said: ↑

Sorry for the slow response.

I should have been more direct with my earlier response.

The set of kinematic equations you have
(v2)²=(v1)²+2ax
(v2)=(v1)+at
x2=x1+(v1)t+1/2at²
are valid for each component of displacement, velocity, and acceleration.

So you have two such sets of kinematic equations:
(v2)_x² = (v1)_x² + 2a_xx
(v2)_x = (v1)_x + a_xt
x2 = x1 + (v1)_xt + 1/2a_xt²

(v2)_y² = (v1)_y² + 2a_yy
(v2)_y = (v1)_y + a_yt
y2 = y1 + (v1)_yt + 1/2a_yt²

It makes sense now. thank you.

SammyS · Sep 10, 2012

PEZenfuego said: ↑

It makes sense now. thank you.

What did you get for answers?