1. Devil physics The baddest class on campus IB Physics

2. Tsokos lesson 2-4 newton’s first law

3. IB Assessment Statements
Topic 2.2, Forces and Dynamics
State Newton’s first law of motion.
Describe examples of Newton’s first law.
State the condition for translational equilibrium.
Solve problems involving translational equilibrium.

4. Objectives
Relate situations in which the acceleration is zero, to equilibrium situations in which the net force is zero
Find the net force on a body using the methods of vector addition
Solve problems of equilibrium

5. Introductory Video

6. Newton’s First Law
When no forces act on a body, that body will either remain at rest or continue to move along a straight line with constant speed.

7. Newton’s First Law
When no forces act on a body, that body will either remain at rest or continue to move along a straight line with constant speed.
What happens when a force acts on a body or when existing forces become unbalanced?

8. Newton’s First Law
When no forces act on a body, that body will either remain at rest or continue to move along a straight line with constant speed.
What happens when a force acts on a body or when existing forces become unbalanced?
Acceleration

9. Newton’s First Law
When no forces act on a body, that body will either remain at rest or continue to move along a straight line with constant speed.
What happens when a force acts on a body or when existing forces become unbalanced?
Acceleration
Acceleration in what form?

10. Newton’s First Law
When no forces act on a body, that body will either remain at rest or continue to move along a straight line with constant speed.
What happens when a force acts on a body or when existing forces become unbalanced?
Acceleration
Acceleration in what form?
Change in velocity
Change in direction

11. Newton’s First Law Also called the Law of Inertia
Reluctance of a body to change its state of motion

12. Inertial Frames of Reference
A system on which no forces act (inert)
Observers in all reference frames should come up with the same answers
Are you an inertial reference frame?

13. Inertial Frames of Reference
A system on which no forces act
Observers in all reference frames should come up with the same answers
Are you an inertial reference frame?
With the rotation of the earth, you have a tangential speed of 464 m/s

14. Inertial Frames of Reference
A system on which no forces act
Observers in all reference frames should come up with the same answers
Are you an inertial reference frame?
With the rotation of the earth, you have a tangential speed of 464 m/s
With the orbit of the earth around the sun, we have a tangential speed of 3x104 m/s

15. Inertial Frames of Reference
A system on which no forces act
Observers in all reference frames should come up with the same answers
Are you an inertial reference frame?
With the rotation of the earth, you have a tangential speed of 464 m/s
With the orbit of the earth around the sun, we have a tangential speed of 3x104 m/s
However, because of the radii involved, the acceleration over short periods of time is minimal

16. Equilibrium Net force on a body is zero
Neutral equilibrium – after a displacement, the sum of the forces acting on the body are still zero
Stable equilibrium – after a displacement, the sum of the forces acting on the body tends to move the body back to its initial position
Unstable equilibrium – after a displacement, the sum of the forces acting on the body tend to accelerate the body away from its initial position
Sum of the forces is key!

17. Objectives
Relate situations in which the acceleration is zero, to equilibrium situations in which the net force is zero
Find the net force on a body using the methods of vector addition
Solve problems of equilibrium

18. IB Assessment Statements
Topic 2.2, Forces and Dynamics
State Newton’s first law of motion.
Describe examples of Newton’s first law.
State the condition for translational equilibrium.
Solve problems involving translational equilibrium.

19. Questions?

20. Homework
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