Unit 2: Forces and Motion

Question 1

Applied Force (Fa)

Answer 1

a general term for the forces that move objects such as rockets, planes, cars, and people
-points in the same direction as the acceleration of the object, canceling out any resistive forces

Question 2

Gravitational Force (Fg)

Answer 2

a field force due to the gravitational attraction between two objects, generally Earth and an object
-points straight down towards the center of the Earth

Question 3

Friction Force (Ff)

Answer 3

The contact force that acts to oppose sliding motion between surfaces (can be static or kinetic)
- points parallel to the surface and usually opposite the direction of sliding

Question 4

Normal Force (FN)

Answer 4

The contact force exerted by a surface on an object
-points perpendicular to and away from the surface

Question 5

Tension Force (FT)

Answer 5

The pull exerted by a string, rope, or cable when attached to a body when pulled taut
-points away from the object and parallel to the string, rope, or cable at the point of attachment

Question 6

Spring Force (Fsp)

Answer 6

a restoring force; that is, the push or pull a spring exerts on an object
-points opposite the displacement of the object at the end of the spring

Question 7

Air Resistance (Ffk)

Answer 7

a special type of frictional force that acts upon objects as they travel through the air
-points opposite the displacement of the object at the end of the spring.

Question 8

Newton’s First Law

Answer 8

An object at rest remains at rest and an object in motion continues in motion with constant velocity (constant speed in a straight line) unless the object experiences a net external.

Question 9

Newton’s Second Law

Answer 9

The acceleration of an object is directionally proportional to the net external force acting on the object and inversely proportional to the object’s mass.

Question 10

Newton’s Third Law

Answer 10

If two objects interact, the magnitude of the force exerted on object 1 by object 2 is equal to the magnitude of the force simultaneously exerted on object 2 by object 1. These two forces are opposite in direction.

always the same type of force but the on’s and by’s switch
ex:

Fn on B by A

Fn on A by B

Question 11

Force

Answer 11

an interaction between two objects that results in a push or a pull

Question 12

Forces can cause… (3 things)

Answer 12

1. a stationary object to move
2. a moving object to stop
3. a moving object to change direction

Question 13

2 Types of Forces

Answer 13

Contact Force
- Forces that result from physical contact between two objects

Field/Long Range Forces
- forces that do not involve physical contact between two objects

Question 14

Kinetic Friction Force (Ffk)

Answer 14

a force that acts to slow down an object in motion
-sliding friction
-resistance force

Question 15

Static Friction Force (Ffs)

Answer 15

a force that acts when an object is on the verge of motion
-prevents object from moving
not moving but it looks like is should move

Question 16

Centripetal Net Force (FnetC)

Answer 16

the net (total) force directed towards the center of an object circular path

Question 17

Centripetal Acceleration (ac)

Answer 17

acceleration directed towards the center of a circular path

Question 18

Tangential Velocity

Answer 18

velocity at the line tangent to the circular path

Question 19

Inertia

Answer 19

The tendency of an object to resist being moved, or if already moving, to resist a change in speed or direction

Question 20

How do we measure inertia?

Answer 20

Mass: the amount of matter in an object, different from the weight

Question 21

weight vs. mass

Answer 21

Mass is the amount of matter in the object and weight is the amount of gravitational pull an object has which can change on different planets.

Question 22

The more mass something has… (inertia increases or decreases)

Answer 22

As mass increases inertia increases, meaning it will take more force to change it’s speed or direction

Question 23

Free Body Diagram

Answer 23

force diagram used to analyze the forces affecting the motion of a single object

Question 24

Force Diagram

Answer 24

a diagram that shows force factors as arrows

Question 25

External Force

Answer 25

a single force that acts on an object as a result of the interaction between the objects and its environment

Question 26

system

Answer 26

the object that is under consideration

Question 27

surroundings

Answer 27

everything else in the environment that might significantly affect the system

Question 28

Action force

Answer 28

The force that object 1 exerts an object 2

Question 29

Reaction Force

Answer 29

the force that object 2 exerts on object 1
not exactly a reaction because it occurs simultaneously with the reaction force

Question 30

weight (Fg)

Answer 30

a measure of the gravitational force exerted on an object

Question 31

Field

Answer 31

a region in which an object experiences a force as a result of the presence of some other object
ex: things on earth experience gravitational force because of it’s presence

Question 32

g=9.8

Answer 32

Earth’s Gravitational Field Strength

Question 33

Newton (N)

Answer 33

The force required to give 1 kg of mass and acceleration of 1 m/s/s

(kgm/s^2)

Question 34

2nd Law Equation:

Answer 34

Fnet = msystem(a)

or

a = Fnet / msystem

Question 35

Assumptions about Friction

Answer 35

1. the relationship between FN and Ff affects friction
2. friction depends on the composition and qualities of the surface and contact with each other

Question 36

Coefficient of Friction (μ)

Answer 36

The quantity that expresses the dependence of frictional forces on the particular surfaces in contact
(a number representing the interactions between surfaces)