- Thanks to Kiwi Co for supporting PBS.
I did fail a math exam, my very first math exam.
I think I got like a 10% or something like that.
- I mentioned before we filmed,
I got a minus five on a math exam once.
- Hey, I'm Diana you're watching Physics Girl.
And I'm here today with Toby, from the Talent Tibees.
One of the other physics channels on the interwebs.
Toby does this really cool thing on her channel
where she unboxes physics exams.
- The concept, you know, you might've seen it with tech
and new iPhones and stuff.
You know, very exciting capture people's reactions.
I do that but with exams.
- We're going to look today at some exams from MIT,
which is where I went for college, specifically 8 0 1 2,
which was my first physics class at MIT it is mechanics,
but we lovingly called it mechanics for masochists
because it was very, very hard.
- We'll have to have a look and see like
what the problems are like and why it would get
that reputation for itself.
- We are going to talk a little bit about exam tips
and tricks at some point for you physics students out there.
All right, let's get to it.
You're going to have to teach me how to do this.
I don't unbox. - Yeah,
so let's do an unboxing.
So in your sleep deprived state,
you open it and you look at this.
So this is the first problem.
And it looks like we're starting off
with some multiple choice and short answer questions.
- [Diana Like the first one here,
two planets are orbiting a star,
two different radi and then they're asking,
which has the greater orbital velocity in,
and which has a greater angular momentums
that you'd need to know, how the orbital speed,
depends on the distance away from the stars.
- You're not just asked for the formula
or to plug numbers in. - Yeah.
- They're actually asking you,
how are these things related? - Yeah.
So maybe that's why it's a harder course.
- Yeah. which is something I really liked about this course
is that it was conceptual,
like you didn't just plug in equations,
you had to know the physics concepts.
- Yeah. - And I think
that's partially why conceptual physics is my favorite way
of thinking about physics.
The math is fun, don't get me wrong.
That's why I'm wearing it all over my jacket.
Cool, next one.
I feel like you should have done the page turn,
- Oh no, no, you need to learn.
- Okay. - You need
to learn the technique.
- Onto problem number two, the Atwood machine.
- These usually take a while to work through.
And they're not that conceptually hard.
It's just usually a bit of algebra determining,
like in part B the acceleration of the lighter blocks.
So knowing how forces are related to acceleration,
I guess F equals ma if you know that much,
you'll probably do okay in the question,
it's a bit intense looking at this.
- It's intense looking and they also,
a lot of times they'll have no friction in problems
like these, but this one they've got
a coefficient of friction.
Lets keep going, ooh, a rocket, oh, ooo, this one looks fun.
Rocket in an interstellar cloud,
I'm going to guess that this problem is something like
you've got this density of particles over here
and you've got a velocity.
So it's how much the rocket slows down or how much it has
to continue boosting itself in order to overcome
the momentum lost from hitting which particles.
- [Toby] So the fact that you're there breaking the rocket
into two different masses,
so I guess rocket science. - [Diana] Yeah.
- [Toby] And the basics of rocket science here.
- This is when math comes into physics,
it's like, you're losing fuel,
but we're going to reflect that in terms of a change in mass
of the rock, which is kind of cool.
- And I think the rocket equation and stuff like this
is actually really cool physics.
My one tip for going into any physics exam
is just F equals ma like here they give it to you
in the question, which is great,
but kind of when in doubt,
try to like smush something into F equals ma
and you'll probably come out with something.
- The problem here is that M is changing.
Moving on.
- [Toby] Moving on, we've got something called sticky disks.
And this looks like a momentum conservation thing.
I guess we could actually read the question,
but that's just my initial thoughts.
And so I, if I had turned over the page
and seen that I would have been ready in my brain with like
momentum is mv and momentum is conserved
in a system like this.
- You know what we haven't done so far,
which I would often do an exam.
- Yeah. - Is to look through all
the questions.
- We could, we could just flick through.
- Yeah, let's do it.
Oh my goodness, this is a very long question.
- [Toby] Obviously something about rotation.
- [Diana] Yes. - [Toby] Like this
has got to be rolling it somehow.
- Next would be, bead on a spinning rod,
man, there's a lot of rotation, but there's also motion, so.
- [Toby] Yeah, it's kind of a lot of cases of things
rolling, moving, rotating and sliding.
- Central potential, okay, so we've got a little bit
of potential energy questions looks like.
- [Toby] Particles, so.
- Oh and then I give you some equations.
That's so nice. - [Toby] Probably not good to
see at the end the exam,
good to see these before you start.
- [Diana] Oh, these are nice.
- [Toby] You can see how these would be useful.
These are like a moment of inertia of different shapes.
- [Diana] Yeah yeah.
These are things that I would not,
like I'm deriving the moment of inertia of different shapes
would take forever.
- We've got F equals ma
- [Diana] There's a potential energy in integral form.
We've got work.
- [Toby] Yeah, you can see that calculus is involved
in this course because they're all written
in like integral form and whatever.
- Okay, cool, I think we're done with 8 0 2 final.
Yay, we passed, high five.
- Show us what you should do.
- Okay, so this is a very first exam that I took
in 8 0 1 2 physics for masochists.
2007, that fateful day.
Okay here's this problem.
Number five out of 25 points, I got one, one point.
so I got an eight out of 10 on the first problem,
so that's good.
Oh, I got the direction of friction wrong.
How could I say that there was
no friction action on the tire?
I wonder what I was thinking, course there's friction.
- Look I think it's a common thing for people to look back
on their exams with the phrase, what was I thinking?
- Circle the point where the magnitude of acceleration
is the greatest, well, I did pretty good there
because all the multiple choice ones, I got it right.
What else have we got?
Oh, I got these right too, yay.
And then it goes downhill from here.
- Yeah, so you can see, you did a lot of algebra.
- Like you had to set up - Yeah.
- these equations and then manipulate them to cancel terms.
And I think that's where people can go wrong.
Cause it was like, you've got, you barely got enough space
to answer the question first of all.
- Yeah yeah.
Hey look, F equals ma, what else have we got?
Watch out, the algebra is what somebody wrote
when they were grading this.
This problem, this is one that I actually remembered
the rest of these poof, gone from my memory,
but this one I remember,
what is the period of oscillation of the disc?
I will never know because I got a zero on it.
- Doesn't like stress make you remember situations more,
which is why you remember this question.
- Maybe so. - Because you
were traumatized.
- I actually did in the end, passed this class.
This was 8 0 1 2, then 8 0 2 2.
I got an A, so I learned how to do MIT.
So can we pause for just one second
and talk about exam tips and tricks, like best practices.
Cause it's been a while since I've taken physics exams,
but I do feel like I learned a lot of techniques.
I didn't really look at practice problems much
before I got to college.
I just sort of thought I knew the material
and I was ready to go.
But as soon as I got to MIT and got to some harder material,
one thing we would do that really helped was looking
at old practice exams - Definitely.
- from previous years of the course,
did you the same? - I almost feel like
that is the most useful way to study for an exam.
Past exams are such a good way to study
because they tell you the format of the problem.
Like even if the problems aren't the same,
they let you know how much time you've got,
how much time you should be allocating.
You're not going to get better
just by only reading solutions, you have to read them
and then try yourself and actually I think
a good thing to do is try until you get stuck.
If you're really stuck and you've explored the avenues,
look at the solutions, but you don't need to look
at the whole thing, you can just look at the first line
that gets you off the hurdle you're on
and then keep going until you get to the next hurdle.
And I think that's a good way to train yourself
how to finish the problem.
Another tip for like exam preparation.
It's kind of related to looking at solutions,
in the same way, but it would be working in a group
for at least a little bit of time while you're studying.
- I experienced nearly failing a number of
my courses freshman year.
I came into MIT not prepared for the rigor of MIT.
I didn't just almost fail this exam, I did fail a math exam,
my very first math exam, I think I got like a 10%
or something like that.
- I mentioned before we filmed,
I got a minus five on a math exam once.
- That's impressive. - I did end up passing
the course with an okay grade as well.
- I ended up passing the class with a B.
So I retook that exam and I got a 90 something
on the retake of the math exam.
And it was just purely from learning how to study
for the exams and the biggest things were doing
the practice problems.
I mean, honestly, that was it, do the practice problems.
- Cause that helps you with everything else.
- Yeah. - It helps with
time management.
- That's 8 0 1 2, thanks for at the exam with me.
- Glad to have done another MIT one.
- It brings back good memories, good and bad.
- Don't be intimidated though.
If you're watching this and you didn't understand
the questions you really need to be in the class.
- Definitely go over and check out Toby's channel.
we did that entrance exam to get into MIT in 1867.
It was really cute.
We just looked at the geometry section,
but I'll put a link in the description.
So check out and subscribe to Toby's channel.
Do you know my sign-off?
- Happy physicsing.
- Yes, thanks so much for watching and
happy physicsing. - Happy physicsing.
- Thanks to Kiwi Co for supporting PBS,
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