Forces & Fields
What do gravitational, electric, and magnetic forces have in common when it comes to influencing objects at a distance?
They all create fields that can exert forces on objects without direct contact.
A student sprinkles iron filings over a sheet of paper with a magnet underneath. What does the pattern of the iron filings reveal about the magnet?
The filings reveal the shape and structure of the magnetic field around the magnet.
If an object’s mass increases, what happens to the gravitational force it exerts on another object?
The gravitational force increases.
A comet moves around the sun in a curved path. What force is responsible for this motion?
The sun’s gravitational force.
What scientific law explains how the mass of two objects and the distance between them determine the gravitational force they experience?
Newton’s Law of Universal Gravitation.
A student observes that a balloon and a small paper scrap are pulled toward each other after rubbing the balloon on a sweater. What type of force is acting here, and does it require contact?
It is an electric force, and it does not require contact.
A student brings a magnet near a pile of paper clips, and some are strongly attracted while others barely move. What does this reveal about the magnetic field around the magnet?
The magnetic field is strongest near the magnet and weaker farther away.
If two objects are the same distance apart, which pair would have the strongest gravitational attraction: one large and one small object, or two objects of equal size?
One large and one small object would have a stronger gravitational attraction.
What effect does gravity have on the motion of planets as they orbit the sun?
Gravity keeps planets in orbit by pulling them toward the sun while their momentum keeps them moving forward.
How does the law of universal gravitation explain why astronauts on the moon experience less gravity than on Earth?
The moon has less mass than Earth, so its gravitational force is weaker.
Some forces can work without touching an object, while others require direct interaction. What is the name for forces that can act without contact?
Noncontact forces.
Why do socks sometimes stick together when taken out of a dryer?
Static electricity causes opposite charges to build up on the socks, leading to an electrostatic attraction between them.
If Earth suddenly had four times its current mass, what would happen to the gravitational attraction it exerts on objects near it?
The gravitational force would quadruple.
How did gravity contribute to the formation of planets in our solar system?
Gravity pulled gas and dust together, forming planets and other celestial bodies.
What would happen to the force of gravity between two objects if the distance between them were doubled?
The gravitational force would decrease to one-fourth of its original strength.
If an object is affected by a noncontact force, in what way does the force act compared to one that requires direct interaction?
Noncontact forces act over a distance, while contact forces require direct physical interaction.
Two charged spheres are placed close to each other, but a nearby plastic object does not move. What does this reveal about the interaction of electric and magnetic fields?
The plastic object is not affected because it does not have charge or magnetic properties.
Why don’t two everyday objects, like a book and a pencil sitting on a table, noticeably move toward each other due to gravity?
Their masses are too small to exert a noticeable gravitational pull on each other.
Black holes have an extremely strong gravitational pull. What property of black holes causes this intense attraction?
Their extremely high mass concentrated in a small space increases gravitational pull.
If you were to travel to a planet with twice the mass of Earth but the same size, how would your weight change?
Your weight would double because gravity is stronger.
Two objects with electric charges attract each other. What would happen if one of them had the same charge as the other instead of the opposite charge?
They would repel each other instead of attracting.
What type of force can both attract and repel objects, depending on certain conditions?
Electric and magnetic forces.
What prevents the force between your hand and an object from keeping it in place when you let go of it?
Earth's gravity is stronger than the force from your hand, so the object falls.
If the sun gradually loses mass, what effect would this have on the orbits of the planets?
The planets would slowly drift farther from the sun because of the weaker gravitational pull.
How does Newton’s law of universal gravitation help scientists predict the movement of celestial bodies like planets and moons?
It allows scientists to calculate the gravitational forces between objects, helping them predict orbits and interactions in space.