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Questions and Answers
A spacecraft is traveling from Earth to the Moon. At which point is the gravitational force of Earth approximately equal to the gravitational force of the Moon on the spacecraft?
A spacecraft is traveling from Earth to the Moon. At which point is the gravitational force of Earth approximately equal to the gravitational force of the Moon on the spacecraft?
- When the spacecraft is closest to the Moon.
- When the spacecraft is closest to Earth.
- When the spacecraft is at a point where the ratio of Earth's gravitational pull to the Moon's gravitational pull is equal to the inverse ratio of their masses.
- When the spacecraft is at a point where the ratio of Earth's gravitational pull to the Moon's gravitational pull is equal to the ratio of their masses. (correct)
A book is at rest on a table. Which of the following statements best describes the forces acting on the book?
A book is at rest on a table. Which of the following statements best describes the forces acting on the book?
- The normal force exerted by the table is less than the gravitational force on the book.
- Gravity is the only force acting on the book.
- The normal force exerted by the table is greater than the gravitational force on the book.
- The normal force exerted by the table is equal in magnitude and opposite in direction to the gravitational force on the book. (correct)
Two objects with different masses are in free fall near the Earth's surface. Neglecting air resistance, which statement is true?
Two objects with different masses are in free fall near the Earth's surface. Neglecting air resistance, which statement is true?
- Both objects experience the same gravitational force.
- The heavier object experiences a greater gravitational force and thus falls faster.
- The lighter object experiences a smaller gravitational force and thus falls slower.
- Both objects experience the same acceleration due to gravity. (correct)
A box is sliding down a ramp at a constant velocity. What can be concluded about the forces acting on the box?
A box is sliding down a ramp at a constant velocity. What can be concluded about the forces acting on the box?
How does the force of friction typically affect the motion of an object?
How does the force of friction typically affect the motion of an object?
Two identical metal spheres, one carrying a charge of $+q$ and the other carrying a charge of $-3q$, are brought into contact and then separated. What is the final charge on each sphere?
Two identical metal spheres, one carrying a charge of $+q$ and the other carrying a charge of $-3q$, are brought into contact and then separated. What is the final charge on each sphere?
A positively charged particle moves perpendicularly through a uniform magnetic field. What is the nature of the force on the particle?
A positively charged particle moves perpendicularly through a uniform magnetic field. What is the nature of the force on the particle?
Which scenario will result in the greatest gravitational force between two objects?
Which scenario will result in the greatest gravitational force between two objects?
A magnet is moved quickly towards a coil of wire. Which of the following factors will increase the induced voltage in the coil?
A magnet is moved quickly towards a coil of wire. Which of the following factors will increase the induced voltage in the coil?
What distinguishes a contact force from a non-contact force?
What distinguishes a contact force from a non-contact force?
Flashcards
Force
Force
A push or pull on an object, measured in newtons (N).
Contact Force
Contact Force
A force requiring direct contact between objects.
Noncontact Force
Noncontact Force
A force that acts between objects without direct contact.
Friction
Friction
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Static Friction
Static Friction
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Sliding Friction
Sliding Friction
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Fluid Friction
Fluid Friction
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Gravity
Gravity
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Mass
Mass
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Weight
Weight
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Study Notes
- Forces change the motion of objects.
Gravity and Friction
- Essential questions include the differences between contact and non-contact forces, the law of universal gravitation, and the effect friction has on the motion of two objects sliding past each other.
Types of Forces
- Force is a push or a pull on an object, and is measured in newtons (N).
- Contact force is a push or pull on one object by another that is touching it.
- Examples of contact force include pushing a container, pressing on computer keys, and friction.
- Noncontact force is a push or pull on one object by another without touching it.
- Examples of noncontact forces include gravity, magnetism, and electricity.
Types of Friction
- Friction is a force that resists the motion of two objects that are touching.
- Static friction prevents objects from sliding past each other.
- Sliding friction opposes the motion of objects sliding past each other.
- Fluid friction occurs between a surface and a fluid like water or air (air resistance).
Static vs. Sliding Friction
- Static friction is when the net force is zero.
- Sliding friction is when there is a net force.
Gravity, Mass and Distance
- Gravity is an attractive force between all objects that have mass.
- Mass is the amount of matter in an object.
- The more mass there is, the more gravitational pull, and the greater the distance, the less gravitational pull.
Weight vs. Mass
- Weight is the amount of gravitational force exerted on an object.
- Weight is measured in newtons (N).
- If an astronaut weighs 539N and has a mass of 55kg on Earth, the weight would change if she was on the moon (F=ma).
Non-contact Force: Electrical
- Static charge is an unbalanced positive or negative charge on an object.
- Opposite charges attract each other, and the same charges repel each other.
- The more charge there is, the greater the electrical force (attraction or repulsion).
- The more distance there is, the less electrical force.
Non-contact Force: Magnetic
- A magnet is an object that attracts metal iron.
- The magnetic pole is the place on a magnet where the force it applies is strongest.
- Opposite poles (charges) attract each other, and the same poles (charges) repel each other.
- The larger the magnet's size, the stronger the attraction.
- The further away magnets are, the weaker the magnetic force will be.
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Description
Learn about forces and how forces change the motion of objects. Explore the differences between contact and non-contact forces. Understand the effect friction has on the motion of two objects sliding past each other, gravity, magnetism, and electricity.
