A toy car is set rolling on a straight track

[Alexanddros81]

Homework Statement

At t = 0, one toy car is set rolling on a straight track with initial
position 15.0 cm, initial velocity -3.50 cm/s, and constant acceleration
##2.40 \frac {cm} {s^2}##. At the same moment, another toy car is set rolling
on an adjacent track with initial position 10.0 cm, initial velocity +5.50 cm/s,
and constant acceleration zero.
(a) At what time, if any, do the two cars have equal speeds?
(b) What are their speeds at that time?
(c) At what time(s), if any, do the cars pass each other?
(d) What are their locations at that time?
(e) Explan the difference between question (a) and question (c)
as clearly as possible

Relevant Equations

none

Hi.
My question is regarding toy car A. If the car moves to the left, is the constant acceleration of ##2.40 \frac {cm} {s^2}##
to the left or to the right?

 

[haruspex]

Hi.
My question is regarding toy car A. If the car moves to the left, is the constant acceleration of ##2.40 \frac {cm} {s^2}##
to the left or to the right?

You should take all positions, velocities and accelerations as positive in the same direction. So if you are taking A's negative velocity as meaning it is moving left then you should take its positive acceleration as meaning it is accelerating to the right.

 

[aerobee]

Positive acceleration has the same direction as positive velocity, so if plus means right then minus means left. So if car A's initial negative velocity is to the left then its acceleration is to the right.
So to visualize, suppose car A is facing right--it's rolling backwards at 3.5 cm/sec when the driver stomps on the gas and accelerates rightward at 2.4 cms2.
[Surely this is a zero-friction environment, so picture it as a rocket car.]

 

[aerobee]

On second thought, it needn't be a zero-friction environment. For example car B's driver could be applying just enough gas to keep its velocity constant.