8PS2 Ch5.1 Reading Essentials - Answers

What do you think? Read the two statements below and decide whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if you disagree. After you've read this lesson, reread the statements to see if you have changed your mind. 1. You pull on objects around you with the force of gravity.

• A (Agree)

• D (Disagree)

What do you think? Read the two statements below and decide whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if you disagree. After you've read this lesson, reread the statements to see if you have changed your mind. 2. Friction can act between two unmoving, touching surfaces.

• A (Agree)

• D (Disagree)

Key Concepts: Contact forces are friction, tension, and normal forces, while noncontact forces are gravitational, magnetic, and electrical forces.

• Friction, tension, and normal forces are contact forces; gravitational, magnetic, and electrical forces are noncontact forces.

• Friction and tension are noncontact; gravity and magnetism are contact forces.

• Only gravitational force is noncontact, and friction is the only contact force.

• Contact forces include only friction, and noncontact forces include only electromagnetism.

Key Concepts: What is the law of universal gravitation? Convert this statement into a concise answer.

• It states that every pair of masses attract each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

• It states that every pair of masses repel each other.

• It states that gravity is the curvature of spacetime.

• It states that earth is the only body that exerts gravity.

Key Concepts: How does friction affect the motion of two objects sliding past each other?

• It opposes the motion, slowing the objects down.

• It accelerates the objects.

• It has no effect on the objects' motion.

• It changes the direction of the objects without affecting their speed.

1. Think it Over

2. 1. Describe. Give an example of a force. - Which below is a good example?

• Gravity

• Heat

• Sound

• Light

Key Concept Check

2. Identify: What are some contact forces and some noncontact forces? Select the correct group of examples.

• Contact forces: friction, tension; Noncontact forces: gravity, magnetism

• Contact forces: gravity, electromagnetic; Noncontact forces: friction, tension

• Contact forces: friction, gravitational; Noncontact forces: tension, normal force

• Contact forces: magnetism, gravity; Noncontact forces: friction, tension

Key Concept Check

3. Identify the law of universal gravitation: It states that every object in the universe attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

• It states that every object in the universe attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

• It describes the acceleration due to gravity as constant for all masses.

• It only applies to gravitational interactions near the Earth's surface.

• It is an outdated concept replaced by modern physics.

Visual Check

4. Interpret How does the gravitational force between objects change if one object increases in mass but the other does not increase?

• The gravitational force decreases.

• The gravitational force increases.

• The gravitational force remains unchanged.

• The gravitational force becomes zero.

Reading Check

5. 5. Explain The effect of distance on gravity is that gravity decreases as distance increases.

• Gravity decreases as distance increases.

• Gravity increases as distance increases.

• Gravity remains the same regardless of distance.

• Distance has no effect on gravity.