DC Physical Science Unit 1

What is Force?

A push or pull exerted on an object

What is force measured in?

Newtons

What is Newton's First Law?

An object in motion wants to stay in motion until acted on by an outside force

What's another name for Newton's First Law?

The Law of Inertia

What is Newton's Second Law? (not the formula!)

A net force causes acceleration

What is Newton's Second Law? (formula)

F = ma

What is Newton's Third Law?

For every action, there is an equal but opposite reaction between two objects.

What's the relationship between mass and acceleration?

The two are inversely proportional

If you hit something with 5N of force how much force will hit you back with?

5N

If two objects exert the same force on each other, which object will have the greater acceleration? The one with larger or less mass?

The object with lesser mass will have a greater acceleration

What are the four Fundamental Forces?

Gravitational Force, Electromagnetic Force, Weak Force, and Strong Force

What is gravitational force?

The attractive force between two objects of mass

Out of the four Fundamental Forces, which one is the weakest but acts over the greatest distance?

Gravitational Force

What is electromagnetic force?

An attractive or repulsive force between two charges

Do opposite charges attract or repel each other?

Attract

Do like charges attract or repel each other?

Repel

What is Weak Force?

The force responsible for nuclear decay

Does Weak Force play a role in fusion or fission?

Weak Force plays a role in fusion

What is Strong Force?

The attractive force that holds the nucleus of an atom together by holding the quarks of protons and neutrons together

What is the strongest of the Four Fundamental forces but acts over the shortest distance?

Strong Force

What force is typically equal to gravitational force?

The force of weight

Weight

Which one exerts a greater gravitational force on the other? The Sun on the Earth or the Earth on the Sun?

Neither, they exert the same gravitational force on each other

What is gravity directly proportional to?

The product of the masses of the objects creating the gravitational force

What is gravity inversely proportional to?

Gravity is inversely proportional to the distance between the masses squared

What is orbital speed?

The speed of an object as it orbits around a larger object

If a moon is orbiting a planet, what is the orbital speed directly proportional to?

The orbital speed is directly proportional to the mass of the planet

If a moon is orbiting a planet, what is the orbital speed inversely proportional to?

The orbital speed is inversely proportional to distance between the moon and planet.

What is orbital period?

The time for one orbit

What is orbital period directly proportional to?

The distance between the orbiting object and what's being orbited

What is orbital period inversely proportional to?

The mass of what's being orbited

What is the gravitational field strength (little g)?

The potential strength of a gravitational field at a particular location from a planet.

On earth, what is the value of the gravitational field strength?

9.8 N/kg

10 N/kg

What is the measurement for the gravitational field strength?

N/kg

Newtons per kilogram of mass

Why is your weight on the moon change while your mass remains constant?

Your weight changes because the Moon has a smaller value of g, which decreases your weight since Fw = mg

What is Kepler's First Law?

Planets travel in elliptical orbits around the Sun

What is Kepler's Second Law?

As a planet gets closer to the Sun, it gets faster

What is Kepler's Third Law?

There is a direct relationship between the period of a planet and it's distance in astronomical units

T^2 is proportional to r^3

What is a perigee and when does it occur for Earth?

The perigee is the shortest radius length while in orbit

Earth's perigee occurs in December

What is an apogee and when does it occur for Earth?

The apogee is the longest radius length while in orbit

Earth's apogee occurs in June

When does a super moon occur?

When a Full Moon is at its closest point in its orbit around the Earth. Because the Moon is closer, it'll appear larger and brighter than a normal Full Moon.

When does an annular solar eclipse occur?

This occurs when the Moon passes directly between the Earth and the Sun but the Moon is close to it's apogee, meaning it's too far from the Earth in it's orbit to fully cover the sun, creating a "ring of fire."

When does a total solar eclipse occur?

When the Moon passes directly between the Earth and Sun and is close enough to the Earth in it's orbit, making it appear as if the Sun is being fully covered.

How do tides compare when the Moon is at perigee compared to apogee?

When the Moon is at perigee, it's gravitational strength is stronger, resulting in higher high tides and lower low tides compared to when it's at its apogee

What is centripetal force?

The force directed towards the center of a curved path and causes circular motion

What direction is the centripetal force compared to the direction of velocity?

The centripetal force is perpendicular to the direction of velocity

What is magnetic force?

The force between magnetic poles or magnetized objects

Do like poles attract or repel?

Two like poles will repel

Do opposite poles attract or repel?

Opposite poles will attract

What is an electromagnet?

A device that uses currents passing through wires to create a magnet whenever the electricity is turned on

What is a motor?

A device that uses electricity and magnetism to create motion

What is electric force?

The force between charged particles or charged objects

How can atoms become negatively charged?

By gaining electrons

How can atoms become positively charged?

By losing electrons

What are three types of charging?

Charging by friction, charging by induction and charging by contact

How does charging by friction occur?

By rubbing two insulators together

What's the result of the objects after charging by friction?

Objects gain opposite charges

How does charging by induction occur?

By bringing a charged object near an uncharged object

What happens after charging by induction?

Uncharged objects acts as if its oppositely charged

How does charging by contact occur?

By touching a charged conductor another conductor

What happens after charging by contact?

Both objects will gain the same charge

What is friction?

The force that resists motion between two surfaces

What is normal force?

The force exerted in a perpendicular direction by a surface

What is applied force?

The force YOU exert on an object

What is a contact force?

Forces that are exerted on an object through contact

What is a field force?

Forces that can be exerted over some distance

When your normal force is less than your weight, do you feel heavier or lighter?

You feel lighter

When your normal force is greater than your weight, do you feel lighter or heavier?

You feel heavier

If there is no normal force, what do you experience?

You experience weightlessness