4.4 Newton’s Laws of Motion

Newton's First Law states:

What is required to change motion of an object?

What is the resultant force if the forces are balanced and the body must be…?

Newton's First Law states: A body will remain at rest or move with constant velocity unless acted on by a resultant force

Resultant force required to change the motion of an object: To speed up, slow down, change direction

Forces on a body are balanced  the resultant force is 0 the body must be: At rest, Moving at a constant velocity

Force is a vector:

Forces are balanced:

Resultant force:

Force is a vector: split the forces into  horizontal and vertical  components

Forces are balanced: forces acting to the left = the forces acting to the right, forces acting upward = forces acting downward

Resultant force: vector sum of all the forces acting on the body

Newton's Second Law states that:

Equation:

Where does acceleration always act?

Unbalanced forces act on an object, object experiences a _______ force

Resultant force acts ____ _____ of the object's _____, the object will:

What would happen if the resultant force acts on object at an angle to its direction of motion?

Newton's Second Law states that: The resultant force acting on an object with a constant mass is directly proportional to its acceleration

F = ma

Acceleration always acts in same direction as resultant force

Unbalanced forces act on an object, object experiences a resultant force

Resultant force acts along direction of the object's motion, the object will: Speed up (accelerate), Slow down (decelerate)

If resultant force acts on object at an angle to its direction of motion, it will: Change direction

Force ______ quantity: ______ and _______

What is a resultant force a sum of

What is the positive direction?

Resultant forces on a body can be ______ or ______ depending on their __________

Resultant force acts at an angle to the direction of motion, the magnitude and direction found by:

Force vector quantity: magnitude and direction

Resultant force is vector sum of all the forces acting on the body

Objects in motion, positive direction is in the direction of motion

Resultant forces on a body can be positive or negative depending on their direction

Resultant force acts at an angle to the direction of motion, the magnitude and direction found by: Combining vectors, Scale drawings

Acceleration ______  quantity: _____ and  _____

Resultant force acts in direction of an object's ______, acceleration is ______

Resultant force ________ direction of object's motion, acceleration is _______

Acceleration acts in the same direction as the resultant force

Acceleration vector quantity: magnitude and  direction

Resultant force acts in direction of an object's motion, acceleration is positive

Resultant force opposes direction of object's motion, acceleration is negative (deaccelerates)

Acceleration acts in the same direction as the resultant force

Newton's second law (momentum)

Change in momentum is in the _______ direction as the ______ force

Newton's second law : The resultant force on an object is equal to its rate of change of momentum

Change in momentum is in the same direction as the resultant force

Newton's Third Law states:

Two objects interact, forces involved are in _____: ______-law pairs

A Newton's third law force pair must be:

Explain diagram

Newton's Third Law states: If Object A exerts a force on Object B, then Object B will exert a force on Object A which is equal in magnitude but opposite in direction

Two objects interact, forces involved are in pairs: third-law pairs

A Newton's third law force pair must be:

Same type of force, same magnitude, Opposite in direction, Acting on different objects

• Foot pushes on the ground and the ground pushes back on the foot.

• Both forces are normal contact force, equal magnitude, opposite in direction, acting on different objects (the foot and the ground)