Kinematics and Dynamics

Question 1

Angstroms

Answer 1

• 10^-10 m

Question 2

Nanometers

Answer 2

• 10^-9 m

Question 3

Electron-volts (eV)

Answer 3

• 1 eV= 1.6 x10^-19 J
• Amount of energy gained by an electron accelerating through a potiential difference of one volt

Question 4

Vectors

Answer 4

• Numbers that have both magnitude and direction
• Displacement, velocity, acceleration, force

Question 5

Scalar

Answer 5

• Numbers that have magnitude only and no direction
• Distance, Speed, pressure, mass, energy

Question 6

Vector Addition

Answer 6

• Tip-to-tail method

1. Place the tail of B, to the tip of A
2. The vector sum A+B is the vector joining the tail of A to the tip of B

• Component method
  1. Given and vector, V, we can find the x- and y-components by drawing a right triangle with V as the hypotenuse

Question 7

Vector Subtraction

Answer 7

• A-B=A+(-B)
• Adding a vector with equal magnitude, but in the opposite direction
• Simply flipping the direction of the vector being subtracted and then following the same rules as normal: tip to tail

Question 8

Multiplying Vectors By Scalars

Answer 8

• If a vector, A, is multiplied by the scalar value, n, a new vector, B, is created
• B= [n] A
• If n is a positive number that means B and A are in the same direction

Question 9

Multiplying Vectors

Answer 9

• To generate a scalar quantity like Work, we multiply the vectors of force and displacement and the cosine of the angle between the two vectors = Dot Product
  1. A *B= [A][B] cos ø
• To generate a third vector like Torque, we multiply the magnitudes of the two vectors of force and lever arm and the sine of the angle between the two vectors
  1. A x B= [A][B] sinØ

Question 10

Displacement

Answer 10

• When an object in motion experiences a change in its position in space
• x or d
• Net change in position from initial to final position

Question 11

Distance

Answer 11

• The entire pathway taken

Question 12

Velocity

Answer 12

• v
• Rate of change of displacement in a given unit of time

Question 13

Speed

Answer 13

• Rate of actual distance traveled in a given unit of time

Question 14

Instantaneous Speed

Answer 14

• Will always be equal to the magnitude of the object’s instantaneous velocity, which is a measure of the average velocity as the change in time approaches zero
• V= Δx/Δt

Question 15

Average velocity

Answer 15

• v_avg = Δx/Δt
• Based on displacement

Question 16

Force

Answer 16

• SI unit is a Newton (N)
• Equation: kg x m/s²

Question 17

Gravitational Force

Answer 17

• Between two objects
• F_g = G m₁ m₂ /r²
• G= universal gravitational constant= 6.67x10^-11 Nm² / kg²
• Would be used on MCAT

Question 18

Acceleration Due To Gravity

Answer 18

• g= 10 m/s²
• Decreases with height above the earth
• Increases the closer one gets to the earth’s center of mass

Question 19

Static Friction

Answer 19

• Always larger than kinetic friction (Always requires more force to get an object to start sliding than it takes to keep an object sliding)
• ( f_<em>s</em> )
• Exists between a stationary object and the surface upon which it rests
• 0≤ fs ≤ u_<em>s</em> N
• u_s is the coefficient of static friction (unitless quantity that depends on the 2 materials in contact)
• N is the magnitude of the normal force (Force between 2 objects in contact that is perpendicular to the plane of contact between the object and the surface upon which it rests

Question 20

Kinetic Friction

Answer 20

• Exists between a sliding object and the surface over which the object slides
• Two surfaces sliding against each other
• f_k = u_k N
• u_k is always smaller than the coefficient of static friction

Question 21

Weight

Answer 21

• F_g = mg
• Weight of the object = F_g
• Mass of the object= m
• Acceleration due to gravity= g (9.8 m/s² )
• Weight of an object can be though as being applied to a single point in the object = Center of mass or gravity

Question 22

Acceleration

Answer 22

• Change in velocity/ change in time
• On a graph of velocity vs. time, the tangent to the graph at any time corresponds to the slope of the graph which indicates the instantaneous acceleration

Question 23

Newtons First Law

Answer 23

• Law of inertia
• A body either at rest or in motion with a constant velocity will remain that way unless a net force acts upon it
• F_net =ma=0

Question 24

Newtons Second Law

Answer 24

• An object of mass, m, will accelerate when the vector sum of the forces results in some nonzero resultant force vector
• F_net =ma

Question 25

Newtons Third Law

Answer 25

• To every action, there is an equal and opposite reaction
• F_AB = -F_BA

Question 26

Linear Motion

Answer 26

• Examples are falling objects, balls being dropped from some starting height
• Equations:

1. v=v₀ + at
2. x=v₀ t +at²/2
3. v²=v^2₀ +2ax
4. x= (average velocity)time

• Free Fall= Object falls with constant acceleration (9.8) and would not reach terminal velocity

Question 27

Drag Force

Answer 27

• An object in free fall will experience as growing drag force as the magnitude of its velocity increases
• Eventually, this drag force will be equal in magnitude to the weight of the object , and the object will fall with constant velocity = Terminal Velocity

Question 28

Projectile Motion

Answer 28

• Usually can assume v_x will remain constant

Question 29

Inclined Planes

Answer 29

• F_g , parallel= mg sinØ
• F_g, perpendicular= mg cosØ

Question 30

Circular Motion

Answer 30

• Instantaneous velocity vector is always tangent to the circular path
• Centripetal force always points inwards, and generates centripetal acceleration
• F_{c = mv²} /r

Question 31

No Net Force

Answer 31

• No acceleration
• Any object with a constant velocity has no net force acting on it

Question 32

Translational Equilibrium

Answer 32

• Constant velocity, both constant speed (zero or nonzero value) and a constant direction

Question 33

Torque

Answer 33

• t= r x F = rF sin Ø

1. r= length of lever arm
2. F = magnitude of force
3. Ø= angle between the lever arm and force vectors

• Clockwise torques= negative
• Counterclockwise torques= positive
• Rotational equilibrium means that the object is not rotating at all
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