Physics - General S2

force

force

a push or pull acting on an object

friction

a force that slows down motion between two surfaces that are touching

Newtons

the unit of measurement for force (N)

gravity

the force that pulls objects down toward the center of the Earth

physics

the branch of science that deals with matter and its motion

smooth surfaces

have less friction

rough surfaces

have more friction

Isaac Newton

one of the most influential scientists of all time; famous for his laws of physics

mass

a measure of how much matter ("stuff") is in an object

weight

a measure of the force of gravity on an object

an object with more mass

has a stronger gravitational pull

an object with less mass

has a weaker gravitational pull

air resistance

force that slows down the motion of objects that move through the air

vacuum

a space without matter or air

all falling objects

fall to the ground at the same rate

net force

the combination of all forces acting on an object

balanced forces

equal forces that combine and form a net force of zero (causes no change to motion)

unbalanced forces

unequal forces that combine and form a net force that is NOT zero (causes change in motion)

Air Resistance

It is the force that opposes motion in the air.

In case of objects falling downward, air resistance will act upward and reduce the acceleration due to gravity.

Terminal Velocity

It is the constant velocity of a falling object when the force of air resistance equals the force of gravity.

It is be the fastest speed reached by a falling object.

Projectile Motion

It is the curved path that an object takes when thrown forward.

It is the result of a combination of the initial forward velocity and the downward velocity because of the vertical force of gravity.

Objects thrown forward or just downward will have the same acceleration and strike the ground at the same time

Newton’s First Law of Motion

An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force.

Newton’s Second Law of Motion

If a net force acts on an object, the object will accelerate in the direction of the net force.

Newton’s Third Law of Motion

for every action (force) in nature there is an equal and opposite reaction

Inertia

the tendency of an object to continue in uniform velocity (or stay at rest)

Which of Newtons Laws are Balanced/Unbalanced

1st → Balanced
2nd → Unbalanced
3rd → Unbalanced

Why is Newton’s first Law balanced?

This law deals with balanced forces because the forces act on the same object and if they are equal in magnitude and opposite in direction, they cancel each other out.

What is the equation of Newton’s Second Law?

Force = mass x acceleration

The acceleration is directly proportional to the force and inversely proportional to the mass of the object.

Give an example of Newton’s Third Law

Examples:

1. Rocket taking off.

The rocket exerts a force on the gases being ejected. The gases apply a force equal in magnitude but in the opposite direction on the rocket, which lifts it off the surface.

2. A book resting on a table

The book applies a force on the table and the table applies an equal force back on the book.

3. Hammering a nail

The hammer applies a force on the nail and the nail applies a force back on the nail. The result is acceleration of the nail into the wall

Force of gravity

The force of gravity is created between any 2 objects with mass. The more the mass, the more gravitational force is present

What is the gravitational force (on earth)

9.8 m/s²

Normal force

This is the force created by a surface to oppose a force pushing on it.

The normal force always matches whatever net force is pushing the object into the surface.

Force of Friction

The force created by a surface on an object that opposes the object’s motion.

The force of friction always acts parallel to the surface and in opposite direction to the motion of the object.

Applied Force

The force of push or pull from a person or another object.

Force of Tension

The force created by the pull of a rope or string.

Tension always pulls in the exact direction of the rope or string itself.

Air resistance

When an object is moving through air, the air applies a force in the opposite direction.

For example, when you stick your hand out the window of a moving car, you feel the force of air pushing against it.

An object experiences more air resistance if it is moving faster or if it has more surface area