I'd like to talk to you about solving
these kinematics problems.
So we're going to actually start by asking ourselves
three separate questions anytime we
start one of these kinematics problems
and this will help us really figure out
what's happening in the motion.
So the first question that we want to ask
is, how many objects are moving?
So do we care about more than one object, and if we do,
we need to make sure to label each one distinctively.
We also want to know how many dimensions we need
to care about for each object.
The second question that we want to ask ourselves
is, how many stages of motion does each object have?
So for an example, if you're told
that a bicycle is initially accelerating
and then, at a certain time, it stops accelerating,
then you know that that initial acceleration
is going to have different equations of motion
than the point in time where it now has
an acceleration equal to zero.
The final thing that we want to think about,
we want to figure out what special conditions there are.
So for example, you might be told that the cart is initially
at rest.
So what does that mean in reality?
It means that you can write down something like, v of 0
is equal to 0, that's what it means for the cart
to initially be at rest.
v cart is-- v at time 0 is equal to 0.
So those are the kinds of special conditions
that you need to pay attention for in the problem
and that will help you figure out--
get all of the numbers or the variables
that you need to solve your equation.
Once you're done thinking through these different steps,
the final thing you should always
do before starting a problem is draw out your problem,
properly label your system, and then of course
draw your origin, your axes, and your unit vectors.
And this way, it will be easy for you
to organize all of the different information that you have.