Question

practice 1: which of the following is true about contact forces?
a. contact forces only work by pushing.
b. contact forces only work by pulling.
c. contact forces require the physical contact between objects.
d. contact forces work between two objects that do not touch.

practice 2: circle the letter of the answer that best describes gravity.
a. gravity only works between planets.
b. gravity is a contact force that holds objects down on earth.
c. gravity is a contact force that holds the moon in orbit around earth.
d. gravity is a non - contact force that holds the moon in orbit around earth.

practice 3: circle the letters of the statements that best describe electrical force. (3 pts)
a. electrical force is found between two charged objects.
b. electrical force is a contact force between two objects.
c. electrical force can be seen between objects with positive and negative charges.
d. electrical force strength depends on charge strength and object distance.

practice 4: circle the letters of the statements that best describe magnetic force. (2 pts)
a. magnetic force is generated by moving electrical charges or aligned atoms.
b. magnetic force is a contact force that can hold objects together.
c. magnetic force is a contact force that can act at a distance.
d. magnetic force can act at a distance to attract objects to each other.

practice 5: match the description with the force. (4 pts)
____magnetic
____electrical
____gravitational
____contact
a. a non - contact force that is generated between charged objects.
b. a non - contact force that exists between objects with mass.
c. a force that requires physical contact between objects.
d. a non - contact force that is generated from moving charges

Explanation:

Practice 1

• Option a: Contact forces can push or pull, so wrong.
• Option b: Contact forces can push or pull, so wrong.
• Option c: By definition, contact forces need physical contact between objects, correct.
• Option d: Non - contact forces work between non - touching objects, so wrong.

• Option a: Gravity works between any objects with mass, not just planets, wrong.
• Option b: Gravity is non - contact, wrong.
• Option c: Gravity is non - contact, wrong.
• Option d: Gravity is a non - contact force and it holds the Moon in orbit around Earth, correct.

• Option a: Electrical force is between two charged objects, correct.
• Option b: Electrical force is non - contact, so wrong.
• Option c: Electrical force exists between positive and negative charges, correct.
• Option d: Electrical force strength depends on charge and distance, correct.

Answer:

c. Contact forces require the physical contact between objects.

Practice 2