Transcript Circular Motion - Lennox Mathematics, Science & Technology

Bell Work Learning Target 1B
Learning Targets
Ranking Task – HW Due Monday
Important Terms
Qualitative
Quantitative
Learning Target 1C
I
can analyze a rotating
system in static
equilibrium using
FBDs and Torque.
Focus Question
 Why
do objects rotate?
Static vs. Dynamic
Question
Describe
the difference
between the two situations,
and justify your answer.
Bell Work – Quantatively prove
your answer
Read the Following pages Due
Monday
IBEs of Rotation
Conditions For Equilibrium
What
must occur in
order for a system to
be in rotational
equilibrium?
Rotation Equalibrium

What is your equation for equilibrium?
Balance: Where should the large
mass be placed? Justify your answer.
CCW
and
CW
What is Torque?
Torque

Torque describes
the ability of a
force to produce a
rotational
acceleration.
Check Yo Self
Defining the parts
Learning Target 1C
Forces at Angles
I Do Learning Target 1C
A uniform meterstick of mass 1kg is
hanging from a thread attached at the
sticks midpoint. One block of mass
3kg hangs from the left end at 0 cm
and another block of unknown mass
hangs at the 80cm mark. If the stick
remains at rest, what is the value of
the unknown mass?
LT 1C Balance: Where should the
mass be placed to produce
equilibrium?
.5 m
5kg
x
1kg
Rotational Equilibrium

Characterisitics
Balance: Where should a third mass
be placed to produce equilibrium?
We Do – Learning Target 1C
You Do Learning Target 1C
Active Practice

Gallery Walk
Prior Knowledge Check 1A,1B
Closure
 How
does Learning Target 1C
connect to material we have
already covered?
Learning Target 1D
I
can analyze a rotating
system with centripetal
acceleration using FBDs
and Newton’s Laws.
Focus Question
 What
happens when an object
rotates?
G-Force Trainer
Circular Motion IBE
Share

Why does the pig move in a circle?

If the string were cut how would the pig
move?

Is the pig accelerating?
Bell Work Learning Target 1A
Learning Targets
Intervention
Learning Target 1D
I
can analyze a rotating
system with centripetal
acceleration using FBDs
and Newton’s Laws.
Share

Why does the pig move in a circle?
The rope is holding it

If the string were cut how would the pig
move?
Tangent to the rotation

Is the pig accelerating?
No it is constant
Motion
What is going to Happen? Why?
What is going to happen to the tape
as the car turns?
Why does the tape slide?
Is it Accelerating?
Question
If
I apply a force will a
mass accelerate?
What is acceleration?
Circular Motion

The object’s velocity is:

However it has an

And it points toward the
Assessment LT 1A Inclines
Centripetal Acceleration

The acceleration that points towards the
center of rotation.
2
v
aC 
r

The time it takes an object to go once
around a circular path is called the period.
2r
v
T
What does this equation tell me?
F  ma
Centripetal Force

Is a force that points towards the center
of rotation.

A centripetal force accelerates an object
by changing the object’s direction without
changing the object’s velocity.
Bell Work LT 1B
Prior Knowledge Check 1A,1B
Centripetal Forces
String Rotating Vertically
What is the object of
focus? Draw the FBD
I Do
A pail of water of 10kg is
rotated in a vertical circle of
radius 1m. What must be the
minimum speed at the top of
the circle if no water is to spill
out?
I Do

A rope of length 1m swings back forth
with a 5kg mass attached to it as pictured
below. If it has a velocity of 5 m/s. What is
the tension at the bottom most point of
its swing?
We Do
A rollercoaster cart has a mass of 500kg
when fully loaded. If the vehicle has a
speed of 20m/s at the bottom, what is the
force of the track on the vehicle? What is
it at the top of the hill
A skateboarder performed a stunt where
he rides his board through a loop.
Assuming the loop has a radius of 2.7m,
what is the minimum speed he needs to
remain in contact with the loop at the
top?
Epic Fail: He doesn’t know his
physics
Curved Track
Draw the FBD
You Do
A car of mass 2000kg rounds a circular
turn of radius 20m. If the road is flat and
 = .7 between the tires and the road,
how fast can the car go without skidding?
Sample
A crate of eggs is located in the middle of
the flatbed of a pickup that negoiates a
curve of radius 35m. If the coefficient of
static friction is .6, what must be the
maximum speed of the truck to prevent
the eggs from sliding during the curve.
Conical Pendulum
Practice
In a swinging mishap, Tarzan whose mass
is 80kg finds himself circling around a tree
in a horizontal circle at the end of a vine
3m long that makes an angle of 5 degrees.
It takes him 10 seconds to complete 1
revolution. Find
a. Centripetal Acceleration
b. Tension of the vine
Active Practice-Bingo
Assessment LT 1A
A 50 Kg block of ice is pushed across the
floor with a Force of 20 N at a constant
speed of 10m/s.
 Draw a free-body diagram of the ice.
 Find the force that the floor pushes up on
the block.
 Find the force due to friction.
 Find the coefficient of friction.

Mind Map
Create
a mind map that
connects all learning targets
together.
Exit Slip
 Explain
why an object moving
in a circular path has an
acceleration.
Exit Slip
What
materials are you
going to use to prepare for
your test tomorrow?
Station Instructions
Max 4 people per station
 3 levels in each station.
 Look at your learning targets and evaluate
your ability.
 You choose the level you are at to
practice and you will explain to me why
you are at that level.
 Workout several problems in your
practice notebook.
 Fill-out reflection on main concepts you
need to focus on.

LT 1D Circular Motion

A frictionless rollercoaster does a vertical
loop with a radius of 6.0m. What is the
minimum speed that the roller coaster
must have at the top of the loop so that it
stays in touch with the rail?
Hard Work Beats Out Talent
Test Analysis
Exit Slip
Bell work LT 1A
No Calculator
Friction Forces
What is acceleration?
Circular Motion

The object’s velocity is:

However it has an

And it points toward the
Centripetal Force Movie Analysis
Exit Slip

At what point on a rollercoaster would I
feel very heavy? Describe with an FBD
and show with equations.