PHY 02 Lesson 8: Newton's Law of Motion

Mechanics

is the branch of physics that deals with the motion of objects.

Kinematics

describes motion

Ex: Distance, Speed, Velocity

Dynamics

causes of motion

Ex: Forces, Gravity

Inertia of rest

- an object will stay in place unless something or somebody moves it.

Example: a plate on the table or standing

Static

study of equilibrium in motion

Inertia of motion

an object will continue at the samespeed until a force acts on it

Example: a rolling bowling ball

NEWTON'S 1st LAW OF MOTION (Law of Inertia)

An object at rest will stay at rest, and an object will continue in motion unless there's a force acting upon it

Inertia of Direction

an object will stay moving in the same direction unless a force acts on it

Example: a moving car turning right

Inertia

is the property of an object that resists changes to its state of motion

The greater the mass of an object, the greater its _________

NEWTON'S 2nd LAW OF MOTION (Law of Acceleration)

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Inertia of rest

Forces

are measured in newtons, using a newton meter.

Isaac Newton

Defined the laws of motion and gravity. Tried to explain motion of the universe.

F=ma

What is the equation for Force?

Newton(N)

SI unit of force

1 kg m/s^2

1 Newton

larger force

A ____________ results in a greater acceleration, but if the object has more mass, it will accelerate less for the same amount of force.

FREE-BODY DIAGRAM

When an object experiences forces, these forces can either push or pull the object in the same direction or in opposite directions.

By looking at the diagram, we can see the type of force acting on the object and the direction in which it is acting.

CONTACT FORCES

is a force that arises when two or more objects are in physical contact with each other.

1. Frictional Force

2. Tensional Force

3. Normal Force

4. Applied Force

5. Air Resistance Force

6. Spring Force

7. Buoyancy

Type of Contact Forces:

Friction

is a force that opposes motion between any surfaces that are touching.

occurs because no surface is perfectly smooth.

❑Rough surfaces have more friction than smooth surfaces.

❑Heavier objects also have more friction because they are pressed harder with greater force than lighter objects.

❑Friction produces heat because it causes the molecules on rubbing surfaces to move faster and have more energy.

Different situation of FRICTION

FRICTION FORCE

Acts opposite to the direction of motion.

AIR RESISTANCE FORCE

Opposes the motion of objects moving through air.

TENSION FORCE

Force transmitted through a string, rope, or cable.

APPLIED FORCE

Force applied by a person or object

NORMAL FORCE

Support force exerted by a surface perpendicular to the object

BOUYANT FORCE

The force that pushes an object upwards in a fluid.

NON-CONTACT FORCE

is a force that can act on an object without touching it.

1. Gravitational Force

2. Electrical Force

3. Magnetic Force

Types of Non-contact Forces

Gravitational Force

Force of attraction or gravitational pull that exists between any two objects with mass.

g = 9.8 m/s2

Electrical Force

Force of attraction or repulsionbetween two charged objects due to their electric charges.

Mass

an amount of matter in something

Is a measurement of how much matter an object contains

Weight

The gravitational pull on a mass

Is a measurement of the gravitational force on an object

NEWTON'S 3rd LAW OF MOTION (Law of Interaction)

❑ For every action, there is an equal and opposite reaction.

❑ When one object applies a force on another object, the second object applies an equal but opposite force back on the first object.

balanced force

is a force in which the net force is equal to zero.

net force

is the total combination of forces acting on anobject.

unbalanced force

is a force in which the net force isgreater than zero.

❑ ___________ cause acceleration.

❑ Only ________________ force can change the motion anddirection of an object.