Unit 5: Forces, Motion, and Gravity

Newton's 2nd Law of Motion

(acceleration) the acceleration of an object is directly proportional to the net force and inversely proportional to its mass

Newton's 3rd Law of Motion

(action and reaction) for every action, there is an equal and opposite reaction

Newton's 1st Law of Motion

(inertia) an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force

How does the relative mass of objects in our solar system (planets, meteors, asteroids, and comets) affect their movement?

A heavier object always has a stronger pull which attracts smaller objects, that can create orbits.

How can a magnet be created?

A magnet can be created by applying an electric current to a metal wire creating a magnetic force: an electromagnet.

How does gravity impact the movement of galaxies and our solar system?

An object's gravitational pull attracts other objects in the universe which can create an orbit, creating systems and galaxies.

How do galaxies form from clumps of dark matter and gas?

By starting thermonuclear fusion (basically gravity kept clustering dust and stuff until they grew bigger)

How does an action force interact with its equal and opposite reaction force? Explain using examples.

Every object exerts an equal and opposite force on any other object. Pushing on a wall, jumping of a boat, a cannonball being shot out of a cannon are examples.

How does Newton's First Law of Motion (objects in motion remain in motion) apply to objects?

Forces stop objects from moving forever, such as friction.

Explain the way gravity works and how it controls movement.

Gravity controls movement because it influences every object that moves in space.

How does gravity impact the movement of galaxies?

Gravity impacts the movement of galaxies because it allows bodies in space orbit other bodies, creating systems and galaxies.

How does the distance between objects affect electromagnetic force?

If the electromagnetic force has a strong enough pull, objects will be attracted to the electromagnet from a closer distance, and vice versa.

How does the orientation of magnets affect their attraction?

Magnets have two poles, a north and south pole, and opposites attract. If the two opposite poles are put together, they become attracted. It you put two of the same poles together, you will feel resistance.

How do orbits work?

Orbits are created when a smaller object in space enters a larger objects gravitational pull creating an orbit. Any object in an orbit is called a satellite.

How can we tell what the center of the Milky Way Galaxy is made of?

Scientists believe that there is a black hole at the center of the galaxy because gravity pulls matter together

What factors affect the strength of electric and magnetic forces?

To increase: wrapping a wire coil around an iron core (solenoid), adding more turns to the coil, increasing the current through the metal coil (basically the opposite to decrease); changing the direction of the current changes the polarity of the field

What are two features that affect the motion of an object?

Velocity (distance/time) and acceleration (distance/time²) affect the motion of an object.

acceleration

a change in speed and direction

solar system

a collection of bodies, including the sun (a star), planets, moons, and asteroids

galaxy

a collection of stars, their associated systems of objects, gas, and dust

gravity

a force that causes every object in the universe to attract every other object

planet

a nearly round rocky or gaseous object that orbits a sun (when asteroids collide, small pieces may break off and become meteoroids)

asteroid

a small rocky body orbiting the Sun (most of the asteroids in our Solar System are found in the asteroid belt between Mars and Jupiter)

electromagnet

a type of magnet created with a magnetic force produced by an electric current; when the electric current is turned off, the magnetic field disappears

distance

affects the electromagnetic force between two objects by the inverse squared (F ∝ 1/d²)

comet

an icy body that releases gas or dust (sometimes called dirty snowballs or snowy dirtballs; might be leftover gas, dust, ice and rocks from the formation of the Solar System 4.6 billion years ago

gravity of objects

an object w/mass will be attracted to every other object w/mass (everyday objects have a very weak gravitational force, so you do not notice them)

orientation/direction of objects

direction determined by poles, or opposite magnetic forces produced at the ends of each magnet; depending on orientation, attraction will change (same repels, opposites attract); poles can have different orientations: diametrically (along the diameter of a circle), radially (inside and outside of a circle), multi-pole, and axially (one charge on top, one on bottom)

velocity (formula)

distance/time

acceleration (formula)

distance/time²

distance and gravity

doubling the distance between objects reduces the gravity by one quarter

mass and gravity

doubling the mass of an object doubles the gravitational pull exerted

equal and opposite

every object exerts an equal and opposite force on any other object

gravity of large objects

gravity on the scale of planets, moons, and stars attract other large objects and shapes in our universe

How does the orientation of two interacting objects affect electromagnetic force?

opposites attracts, same repels

mass of objects (order)

planet, comet, asteroid, meteoroid (meteors)

meteoroid (meteors)

small rocky objects that orbit the sun (when meteoroids come close to Earth, they become meteors)

velocity

the speed of something in a given direction

How can Newton's Third Law of Motion be applied to explain how objects collide?

when (two) objects collide, they press against each other with equal force in opposite directions

action and reaction with different masses

when two objects with unequal mass collide, they will accelerate at different rates (the smaller object accelerates more)

How does Newton's Second Law of Motion (F=m*a) apply in the real world?

The greater the mass and force, the greater the acceleration. Ex: when sledding, your weight and gravity pushing you down the hill is acceleration

How does mass affect the gravitational pull between two objects in the solar system?

The greater the mass, the stronger the pull between two objects in a solar system, and if the mass decreases, the pull weakens.

What evidence could you provide to explain how gravitational pull and movement changes with the mass of two objects?

The greater the mass, the stronger the pull between two objects in a solar system, and if the mass decreases, the pull weakens. When the pull is stronger, the object's orbit closer to each other. In the Phet simulation, the bigger the object, the stronger the pull.