**Define normal force**, N, as the force or the component of a force which a surface exerts on an object with which it is in contact, and which is perpendicular to the surface.**Define frictional force**, f, as the force that opposes the motion of an object and which acts parallel to the surface.

**Define static frictional force**, f_{s}, as the force that opposes the tendency of motion of a stationary object relative to a surface.

**Define kinetic frictional force**, f_{k}, as the force that opposes the motion of a moving object relative to a surface.

**Know that a frictional force:**

• Is proportional to the normal force

• Is independent of the area of contact

• Is independent of the velocity of motion

- Solve problems using:

is the maximum static frictional force and:

**u**_{s}

is the coefficient of static friction. - If a force, F, applied to a body parallel to the surface does not cause the object to move, F is equal in magnitude to the static frictional force.
- The static frictional force is a maximum

just before the object starts to move across the surface. - If the applied force exceeds

,

a resultant/net force accelerates the object. - Solve problems using:

where f_{k}is the kinetic frictional force and u_{k}the coefficient of kinetic friction.

- Draw
**force diagrams** - Draw
**free-body diagrams**. (This is a diagram that shows the relative magnitudes and directions of forces acting on a body/particle that has been isolated from its surroundings) **Resolve**a two-dimensional force (such as the weight of an object on an inclined plane) into its parallel (x) and perpendicular (y) components.- Determine the
**resultant / net force**of two or more forces.

**State**Newton's First Law of motion: A body will remain in its state of**rest**or motion at**constant velocity**unless a non-zero resultant / net force acts on it.**Discuss**why it is important to wear**seatbelts**using Newton's First Law of motion.**State**Newton's Second Law of motion: When a**resultant/net force**acts on an object, the object will**accelerate**in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.**Draw force diagrams and free-body**diagrams for objects that are in equilibrium or accelerating.**Apply Newton's laws**of motion to a variety of equilibrium and non-equilibrium problems including:- A single object:

- Moving on a horizontal plane with or without friction

- Moving on an inclined plane with or without friction

- Moving in the vertical plane (lifts, rockets, etc.) - Two-body systems (joined by a light inextensible string):

- Both on a flat horizontal plane with or without friction

- One on a horizontal plane with or without friction, and a second hanging vertically from a string over a frictionless pulley

- Both on an inclined plane with or without friction

- Both hanging vertically from a string over a frictionless pulley

- A single object:
**State**Newton's third law of motion: When one body exerts a force on a second body, the second body exerts a**force of equal magnitude**in the**opposite direction**on the first body.- Identify
**action-reaction**pairs. **List**the**properties**of action-reaction pairs.

**State**Newton's Law of Universal Gravitation: Each body in the universe attracts every other body with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.**Solve**problems using:

**Calculate**acceleration due to gravity on a planet using:

**Describe weight**as the gravitational force the Earth exerts on any object on or near its surface.**Calculate weight**using the expression:

w = mg.- Calculate the
**weight**of an object on**other planets**with different values of gravitational acceleration. **Distinguish**between**mass****and**.**weight**- Explain
.**weightlessness**