contact force
What is a contact force
a force that does not need contact
What is a non-contact force?
A non-contact force is a force that can act on an object without touching it.
How does gravity affect objects on Earth?
Gravity pulls objects toward the Earth’s surface, keeping us from floating and making things fall when dropped.
How does static electricity work as a non-contact force?
Static electricity occurs when objects gain or lose electrons, causing them to attract or repel other objects without touching. For example, rubbing a balloon on your hair makes it stick to a wall!
What happens when you bring two magnets close to each other?
If the poles are opposite (north and south), they attract. If the poles are the same (north and north or south and south), they repel.
Example of contact force
pushing a door
What are some examples of non-contact forces?
Examples of non-contact forces include gravity, magnetism, and electrostatic force.
Why do things fall to the ground when dropped?
Things fall because of gravity, a non-contact force that pulls objects toward the center of the Earth.
What is static electricity?
When electrical charges move from one object to another, they can cause static electricity. Picture this, you rub your hair against a balloon. The negative charges in your hair move to the balloon causing more negative charges in the balloon.
The extra negative charges on the balloon create what is called a buildup of negative charges. You can’t see the extra negative charges but try bringing that balloon near a wall. The extra negative charges in the balloon will become attracted to the positive charges in the wall and they will stick together.
How do magnets work as a non-contact force?
Magnets can attract or repel objects made of iron, nickel, or cobalt without touching them, using magnetic force.
how does contact force affect objects
Contact force can cause objects to move, change shape, or change direction depending on how it is applied.
What makes a non-contact force different from a contact force?
A non-contact force can act on objects without touching them, while a contact force requires physical touch to work.
What is the difference between gravity and weight?
Our weight is based on gravity. Weight is the measurement of the force of gravity pulling us down. This means our weight is how hard gravity is pulling us towards the Earth’s surface.
On other planets or on the moon, we weigh a different amount because their gravitational pull is stronger or weaker. Someone weighing 100 pounds on Earth would weigh only 16 pounds on the moon. This means that gravity’s force is not very strong on the moon. If you applied a pushing force into the ground by jumping, you would go a lot higher on the moon because there is less pulling force bringing you back to the moon’s surface.
What is lightning?
Lightning is an electrostatic current that travels from one electrically charged object to another. When a thundercloud forms,
raindrops bump into each other causing a static electric charge. In the diagram, you can see the thundercloud is becoming negatively charged at the bottom. When this happens, the positively charged objects on the earth’s surface will become attracted to the negatively charged thundercloud. Once the charge is strong enough, their attraction will cause lightning, which is an electrical current between the two objects that are oppositely charged.
What is a magnet?
A magnet is an object that can attract or repel other magnets. We sometimes say someone is magnetic if they attract a lot of friends.
Magnets have a north and a south pole. You can attach two magnets by putting opposite poles together. If you try to put the same poles together, they will repel each other.
What are some types of contact forces?
Some types of contact forces include frictional force (resistance to motion between surfaces), normal force (support force exerted by a surface), tension force (pulling force transmitted through a rope, string, or similar object), and applied force (force exerted by a person or object).
Can non-contact forces work in space?
Yes! Gravity keeps planets in orbit, and magnetic fields exist in space, even though there is no air or physical contact.
Would you weigh the same on the Moon as on Earth? Why or why not?
No! You would weigh less on the Moon because the Moon has weaker gravity than Earth.
Why do your clothes sometimes stick together after being in the dryer?
The clothes rub against each other and build up static electricity, causing them to cling together due to electrostatic force.
How can you magnetize a metal object?
Striking
To perform this technique, align your object so that it is pointing along the north south axis of the Earth. You can use a compass to find out which direction this is. Strike the object with a hammer repeatedly. This shakes the atoms out of their original spots, causing them to realign to the Earth’s magnetic field. Now your object will become a magnet that attracts other magnetic materials. Eventually the object will lose its magnetic powers as the atoms line up in their original spots.
Why do we need contact force in our daily life?
Contact force helps us do many everyday activities. For example, we need contact force to write with a pencil (applied force), walk without slipping (frictional force), and sit on a chair without falling (normal force). Without contact force, objects wouldn’t move or stay in place properly!
How does the Moon stay in orbit around the Earth without touching it?
The Moon stays in orbit because of Earth's gravity, which pulls it toward Earth while its motion keeps it moving around. This is an example of a non-contact force at work!
Why don’t we float away from Earth?
We don’t float away because Earth’s gravity pulls us down and keeps us on the ground.
What happens when two objects have the same charge?
They repel (push away from) each other, just like two magnets with the same poles.
What is a compass?
A compass is a navigational tool that tells people which direction they are going. The compass was invented in 1300 by an Italian explorer named Flavia Goia. Combined with a map, a compass was very important for
sailors to know which direction they were going. This is because when you are in the middle of an ocean, you cannot
see any landmarks other than the sun. Therefore, it is impossible to know which direction you are going!