Forces and Motion Lecture Review

Comprehensive practice question-and-answer flashcards covering forces, motion, friction, gravity, magnetic fields, and electromagnets from the lecture notes.

What is an example of a force acting at a distance (non-contact force)?

A magnet pulling a paperclip

What type of force is gravity?

A field/non-contact force

What is the net force on an object if two equal forces act on it in opposite directions?

$0$ (zero)

If the net force on a moving object is zero, what will happen to its motion?

It will continue moving at the same speed and direction

Which force opposes the sliding motion of two surfaces?

Friction force

In which direction does drag act on an object moving through a fluid?

In the opposite direction of the object's motion

What is the force that acts between charged objects called?

Electrostatic force

What kind of object has a gravitational field?

Any object with mass

What two factors determine the weight of an object?

Mass and gravitational field strength

If you take an object to the Moon, what happens to its mass and weight?

Mass stays the same, and weight decreases

What do magnetic field lines show?

The direction and strength of the magnetic field

What happens when two magnets with opposite poles face each other?

They attract

What is an electromagnet?

A magnet made by an electric current

Which forces are examples of forces that act at a distance?

Magnetic, electrical, and gravitational forces

What best describes kinetic friction?

Friction opposing motion between sliding surfaces

What happens to an object when the forces acting on it are unbalanced?

It changes its speed or direction

What is a force diagram used to show?

The forces acting on an object

What does the length of an arrow represent in a force diagram?

Magnitude (strength) of the force

If an object is moving in a circle around a center point, what is the force causing this motion called?

Centripetal force

How do electrostatic (electrical) forces behave depending on charges?

They can attract or repel depending on the charges

What are three defining characteristics of friction?

It opposes motion, always acts in the direction opposite to motion, and can cause moving objects to slow down

What happens to the gravitational force between two objects if the distance between them increases?

The gravitational force decreases

Which phenomenon causes electric currents to produce magnetic fields?

Electric currents themselves

What type of force is drag?

A contact force opposing motion through a fluid

How does an object's mass affect the gravitational force it experiences?

The more mass an object has, the greater the gravitational force (e.g., a bowling ball experiences more gravitational force than a baseball or feather)

What is the direction of the gravitational force on an object near Earth?

Toward the center of the Earth

What happens to the speed of an object if a net force acts in the same direction as its motion?

The speed increases

What is an example of a magnetic force in action?

A compass needle pointing north

How can you tell if the forces acting on an object are balanced?

The object is at rest or moving at a constant speed (constant velocity)

What describes an electrostatic/electrical field?

A region around a charged object where electric forces can be felt

What will happen to the gravitational force if you increase the mass of one object in a gravitational field?

The gravitational force increases

Which force is responsible for a satellite orbiting Earth and planets orbiting the Sun?

Gravitational force

What happens to magnetic forces when two magnets are aligned with like poles facing each other?

They repel

What is an example of an electromagnet?

A coil of wire with an electric current

What is the role of friction in everyday life?

It helps us walk without slipping, slows down moving objects, and causes heat when rubbing hands

If multiple forces act on an object, how do you find the net force?

Add all forces considering their direction

Which force causes a book to stay on a table without falling?

Normal force

What happens to an object's motion if the net force acting on it is directed opposite to its motion?

It slows down

What happens when electric current flows through a wire coil wrapped around an iron nail?

The nail becomes an electromagnet

What is the effect on an object's motion when a net force acts perpendicular to its current motion?

The object changes direction

Which force acts on a falling object and slows it down?

Drag

What best describes a force field?

A region around an object where forces can act without contact and you cannot see

What is the difference between mass and weight?

Weight depends on gravity, whereas mass does not

Why do objects continue moving in space without slowing down?

There is no friction or drag in space

What is true about electromagnets when electric current stops?

They lose magnetism when electric current stops

What happens to a moving object's speed if friction increases?

The speed decreases