This unit investigates the causes of motion and how to better understand them. Newton's Laws and free body diagrams are a central topic of study.
"I Can" statements (learning goals) for the unit:
I can describe how forces affect the motion of an object.
a. I can identify the SI unit of force = Newton (N).
i. I can describe the Newton in terms of its constituent parts (1 N = 1 kg m/s2).
b. I can differentiate between contact and field forces and provide examples of each.
i. Contact Forces
1. Applied force (FA)
2. Normal force (FN) – perpendicular to the surface
3. Tensional force (FT)
4. Frictional force (Ffr)
a. Compare static and kinetic forces of friction.
b. Identify coefficient of friction as a ratio of frictional and normal forces.
c. Static force of friction
i. Apply the equation Ffr = µsFN .
d. Kinetic force of friction
i. Apply the equation Ffr = µkFN .
5. Elastic force
ii. Field Forces
1. Gravitational Force (Fg)
a. Apply Newton’s Law of Universal Gravitation to show how the masses of objects as well as distance between objects produce gravitational force.
2. Electric Force
3. Magnetic Force
4. Strong/Weak Nuclear Forces
c. I can use free body diagrams using vectors to describe multiple forces acting on a body.
i. On a horizontal surface
1. Force of gravity (W = mg)
2. Normal force (FN = Fg)
3. Applied force (FA)
a. Tensional force (FT)
4. Frictional force (Ffr) – opposing motion
ii. On a tilted surface
1. Force of gravity (W = mg)
2. Normal force - perpendicular to the surface (FN ≠Fg,) : resolve into components
3. Applied force (FA): resolve into components
a. Tensional force (FT)
4. Frictional force (Ffr) – opposing motion
iii. Find the net force on an object when multiple forces are acting on an object.
2) I can use Newton’s Laws of Motion to describe how forces affect the motion of an object.
a. I can define and use Newton’s First Law of Inertia to describe how forces affect the motion of an object in and out of equilibrium.
i. Mass is proportional to the inertia of an object.
ii. Compare situations with varying net forces.
1. In equilibrium
a. Objects at rest with net force of zero.
b. Objects in motion with net force of zero.
2. Out of equilibrium
a. Objects initially at rest with unbalanced forces.
b. Objects in motion with unbalanced forces.
b. I can define and use Newton’s Second Law to describe how forces affect the motion of an object.
i. I can predict proportionality between net force, mass, and acceleration of an object.
ii. Using Newton’s definition for forces, I can predict acceleration based on the mass of an object (∑Fnet = ma).
iii. I can apply the laws of kinematics to describe the motion of bodies acting due to forces.
c. I can define and use Newton’s Third Law to describe how forces affect the motion of an object.
i. I can identify force pairs and the direction and magnitude of the force on each object.