1. Review test, introduction to dynamic forces
Friday, September 23, 2016

2. Unit 3: Dynamic Forces Friday, 9/23
Analyze the photo to the right and
respond to the following:
How does the mass, velocity,
displacement, and time passage,
of the object (diver) change from
the top of the cliff to the bottom?
Upcoming important dates
Friday, 9/23 – HWK quiz (cancelled)
Tuesday, 9/27 – homework quiz
Thursday, 9/29 – homework quiz
Monday, 10/3 – Newton’s
2nd and 3rd law quiz
Wednesday, 10/5 – Friction quiz
Friday, 10/7 – homework quiz
Wednesday, 10/12 – unit quiz
Friday, 10/14 – unit test (note grade
goes on 2NWS)
Image source:
commons/5/59/Acapulco_Cliff_Diver.jpg

3. Review Test Pick up test and a sticky note.
If you have questions about your test, write it on a sticky note and place it on your test.

4. Unit 3: Dynamic Forces Thursday, 9/22
Analyze the photo to the right and
respond to the following:
How does the mass, velocity,
displacement, and time passage,
of the object (diver) change from
the top of the cliff to the bottom?
Image source:
commons/5/59/Acapulco_Cliff_Diver.jpg

5. Where we’ve been…
Inertia (Newton’s first law of motion) applies when forces are balanced.
Object is at rest
Object is moving at a constant velocity
We’ve used vectors, FBDs, and Net Force equations to analyze objects which have balanced forces

6. Where we are going… Analyzing objects with unbalanced forces!
Viewing unbalanced forces through multiple lenses; acceleration, momentum, energy.

7. Unbalanced Forces
Result in a change in velocity meaning the object is accelerating.
Results in a net force greater than zero
Example:
The object represented in the FBD
has a mass = 6 kg.
Calculate the weight of the object.
Calculate the net force
Determine the direction the object
will move.

8. Acceleration - magnitude
Final velocity, m/s
Initial velocity, m/s
Change in time, s

9. Acceleration magnitude and direction
An 800-kg car is coasting to the right with a leftward acceleration of 1 m/s2. Diagram the forces acting upon the car.

10. An 800-kg car is coasting to the right with a leftward acceleration of 1 m/s2. Diagram the forces acting upon the car.
Big idea: an object can be accelerating in one direction and
moving in a different direction.

11. Newton’s 2nd
Unbalanced forces cause a change in the motion of the object.
The amount of change is dependent on the magnitude of the force and the mass.
larger force = larger change in motion
larger mass = small change in motion
Amount of change can be expressed in three different ways.

12. Newton’s 2nd Law of motion expressions
Acceleration
Momentum
Kinetic Energy
a =ΣF m
Units: m/s2
Relationships:
p = mv
Δp = ΣFΔt
Units: kg * m s
Relationships:
K = ½mv2
∆K =ΣF∙d
Units: N*m or Joule (J)
Relationships:

13. Momentum When watching the video do the following:
What systems are acting on the puck?
What determines the acceleration of the puck when it makes contact with the stick?
How was the term energy used?

14. Energy When watching the simulation analyze the following:
The relationship between velocity and kinetic energy for the roller coaster car (Ex: does it change, if does change what is the contributing variable to the change?

15. Newton’s 2nd Law of motion expressions
Acceleration
Momentum
Kinetic Energy
a =ΣF m
Units: m/s2
Relationships:
p = mv
Δp = ΣFΔt
Units: kg * m s
Relationships:
K = ½mv2
∆K =ΣF∙d
∆K = Kf - Ki
Units: N*m or Joule (J)
Relationships:

16. A net force of 50 N is exerted on a 25 kg object for 4s, during which time the object started from rest and moved forward 16 meters. Calculate: G:
Acceleration
Momentum
Kinetic Energy
U: a =ΣF m
U: p = mv Δp = ΣFΔt
U: K = ½mv2 ∆K =ΣF∙d ∆K = Kf - Ki

17. Home work review – 20 minutes
With your row, review your homework.
After you have discussed the homework
Decide which question is still ‘muddy’ and place a check mark next to the question number on the board (one question per section)

18. Homework Quiz

19. Homework Review notes from today.
Complete any unfinished homework questions.

20. Cool Down
How are acceleration, momentum, and energy connected?