Example Problem A man at the top of a building drops a ball. It takes 3 seconds for the ball to fall...

Example ProblemA man at the top of a building drops a ball. It takes 3 seconds for the ball to fall to the ground, how tall is the building?

Example ProblemA man is running with a constant velocity of 9 m/s and covers a distance of 27 m? How long was he running for?

Example ProblemA man throws a ball horizontally from the top of a building with a velocity of 9 m/s. If the ball lands 27 m from the edge of the building, how tall is the building?

9 m/s

Physics HonorsA/B–Day 11/1/15

Newton’s Laws

Isaac Newton• Conceived Calculus• Described Planetary Motion• Designed and Constructed Reflecting Telescope

Newton’s Laws of Motion• Seen as Father of Physics• Newton’s Laws are laid down in

Newton’s Principia

• Gravity is Universal

Newton’s First Law of Motion• An object in motion continues in motion with the same

velocity unless acted upon by an unbalanced force; an object at rest will tend to stay at rest

The Law of Inertia

Newton’s First Law of Motion• Inertia – the tendency of an object to maintain it’s state of

motion• Inertia developed by Galileo•Mass is a quantity that is determined by the inertia of the

object• Inertial Mass

What is a Force?•Force - Any influence that causes a change in an

object’s velocity

•Vector• Can be a contact or Field Force• SI Unit is a Newton

How do you represent Force?• Force Vector represents magnitude and direction

•

Force Diagrams• Force • Can be in equilibrium (balanced) or could be

causing acceleration (unbalanced)

Forces addition or subtraction

• Parallel Forces add or subtract • Perpendicular Forces do not affect each other

Newton’s First Law of Motion• Example of 1st law would be if you ever sat in a truck

and it stopped.

Newton’s Second Law of Motion• The acceleration of an object is directly proportional to the

net external force acting on the object and inversely proportional to the objects mass

m is the mass (kg)

Newton’s Second Law of Motion

• Balanced Forces cause equilibrium • Moving or staying constant velocity

• Unbalanced Forces – cause object to accelerate

Newton’s 2nd Law of Motion• What is a Balanced Force? Object at Rest or moving at a constant velocity

Newton’s 2nd Law of Motion• What is an unbalanced Force? Object in Motion.

Newton’s Third Law of Motion• If two objects interact, the magnitude of the force exerted on object

1 by object 2 is equal to the magnitude of the force simultaneously exerted on object 2 by object 1 and these two forces are in opposite direction• Every action has an equal and opposite reaction

How do you represent multiple forces on an object?

• Graphically Forces can be shown on a free body diagram

𝐹 𝑎𝑝𝑝𝑙𝑖𝑒𝑑

→

𝐹 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛

→

𝐹 𝑛𝑜𝑟𝑚𝑎𝑙

→

𝐹 h𝑤𝑒𝑖𝑔 𝑡

→

Practice Problem• Draw a free body diagram for a book on a table not

moving.

Practice Problem• Draw a free body diagram for a book on a table

moving at a constant velocity.

Practice Problem• Draw a free body diagram for a book on a table

moving with a changing velocity (accelerating).

Practice Problem• Draw a free body diagram for a book on an inclined

plane not moving.

Practice Problem• Draw a free body diagram for a book sliding down an inclined

plane with no friction.• 2.0 kg

Homework – Due 11/06/15

•Watch Videos on youtube Channel “Flipping Physics” Forces and Newton’s Laws of Motion