Catching up

Hi, ive got a big probllem:

When you are 20m away from your bus it begins accelerating a 3m/s/s (from rest). What constant velocity should you run at to catch the bus.

HELP!!!!!!!!!!!!!!!
jason

theres i big chance no one will help you unless you show an attempt

Tom Mattson
Staff Emeritus
Gold Member
Yep, you have to show that you've made an attempt.

Tom Mattson said:
Yep, you have to show that you've made an attempt.
thats the think I have no idea where to begin

The fruit of my labors is:
me:
Vi=?
Vf=?
t=?
a=0
d=to bus

bus:
Vi=0
Vf=?
t=?
a=3m/s^2
d=to bus
This enough? because otherwise i am sol

Last edited:
Try drawing two pictures; the first showing the initial conditions, and the second showing the final conditions when you've caught the bus.

Once you've drawn the pictures, make sure you listed all your knowns.

List your kinematics formulas so you can see what you have to work with.

And don't forget to note your initial and final position.

Try choosing your initial position as zero, which would make the initial position of the bus 20 m.

*melinda* said:
Try drawing two pictures; the first showing the initial conditions, and the second showing the final conditions when you've caught the bus.
Once you've drawn the pictures, make sure you listed all your knowns.
List your kinematics formulas so you can see what you have to work with.
And don't forget to note your initial and final position.
Try choosing your initial position as zero, which would make the initial position of the bus 20 m.
i have drawn a picture, listed my formulas( no idea which 1 to use though)

Tom Mattson
Staff Emeritus
Gold Member
You have yet to make use of that 20m in the problem statement. Let the motion be along the x-axis.

Can you fill in the following information?

Runner: xi=?
Bus: xi=?

Tom Mattson said:
You have yet to make use of that 20m in the problem statement. Let the motion be along the x-axis.
Can you fill in the following information?
Runner: xi=?
Bus: xi=?
ive been working more but all i have still is:thats the think I have no idea where to begin

me:
Vi=?
Vf=Vi (constant)
t=?
a=0
d=to bus-20

bus:
Vi=0
Vf=?
t=?
a=3m/s^2
d=to me+20

Tom Mattson
Staff Emeritus
Gold Member
In order to answer my question, you need to choose an origin for the coordinate system. Let's just put the runner's initial position at the origin, and let the bus sit to the right of the runner.

Now can you fill in those values?

me:
Vi=?
Vf=Vi (constant)
t=?
a=0
d=distance run

bus:
Vi=0
Vf=?
t=?
a=3m/s^2
d=to run-20

Tom Mattson
Staff Emeritus
Gold Member
What I am asking you to do is assign an x-coordinate to both the runner and the bus initially. Do you know what a coordinate on a graph is?

x would be distance and y would be time right?

Tom Mattson
Staff Emeritus