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MCAT Physics + Math > Ch 1 - Kinematics and Dynamics > Flashcards

Ch 1 - Kinematics and Dynamics Flashcards

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1
Q

What are the base SI units for length, mass, time, current, amount of substance, temperature, and luminous intensity?

A
  • length: meter (m)
  • mass: kilogram (kg)
  • time: second (s)
  • current: ampere (A)
  • amount of substance: mole (mol)
  • temperature: kelvin (K)
  • luminous intensity: candela (cd)
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2
Q

What are the derived SI units for force, work/energy, and power?

A
  • force: newton (kg.m/s^2)
  • work/energy: joule (kg.m^2/s^2)
  • power: watt (kg.m^2/m^3)
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3
Q

What are vectors?

A

physical quantities that have magnitude and direction

- displacement, velocity, acceleration, and force

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4
Q

What are scalars?

A

quantities that have magnitude only and no direction

- distance, speed, energy, pressure, and mass

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5
Q

What is the resultant?

A

the sum or difference of 2+ vectors

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6
Q

How do you add vectors using the tip-to-tail method? Is it commutative?

A
  • tip-to-tail method: A+B, place the tail of B at the tip of A without changing either length or direction of either arrow; the sum is the vector joining the tail of A to the tip of B and pointing toward B (commutative; A+B = B+A, no difference)
  • by breaking a vector into its components and using the Pythagorean theorem
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7
Q

What are the component vector equations?

A
  • X = Vcos; Y = Vsin
  • sin30 = 1/2
  • cos30 = root3/2
  • sin90 = 1
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8
Q

How do you subtract vectors? Is it commutative?

A
  • add a vector with equal magnitude, but opposite direction, to the first vector
    A-B = A + (-B)
  • flip direction of vector being subtracted and then follow tip-to-tail method
  • not commutative; A-B has same magnitude as B-A but oriented in opposite direction
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9
Q

How do you solve for the resultant vector when adding or subtraction?

A
  • add: Rx = sum of all x-components and Ry = sum of all y-components
  • subtract: Rx = difference of all x-components and Ry = difference of all y-components
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10
Q

How do you multiply vectors by scalars?

A
  • if a vector A is multiplied by a scalar n, a new vector B is formed: B = nA
  • to determine direction of B, multiple by the absolute value of n. if +n, +B. if -n, -B
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11
Q

What is the dot product (vector x vector)?

A
  • to generate scalar quantities like work, multiply the magnitudes of 2 vectors of interest (force x displacement) and the cosine of the angle between the vectors
  • A . B = |A| |B| cos angle
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12
Q

What is the cross product (vector x vector)?

A
  • when generating a third vector like torque, need both magnitude and direction so multiple the magnitude of the 2 vectors (force x lever arm) and the sine of the angle between them. then use right hand rule to determine direction
  • A x B = |A| |B| sin angle
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13
Q

How do you apply the right hand rule?

A
  • start by pointing your thumb in the direction of vector A (x vector)
  • extend your fingers in the direction of vector B by rotating wrist (y vector)
  • your palm establishes the plane between the 2 vectors. the direction your palm points is the direction of resultant C
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14
Q

What is the difference between displacement and distance?

A
  • displacement: (vector quantity) when an object in motion may experience a change in position in space; connects initial and final position with straight line
  • distance: (scalar) travel considering the pathway taken
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15
Q

What is the difference between velocity and speed?

A
  • velocity (vector): rate of change of displacement in a given unit of time, same direction as displacement
  • speed (scalar): rate of actual distance traveled in a given unit of time
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16
Q

What is the difference between instantaneous velocity and instantaneous speed?

A
  • velocity: the limit of change in displacement over time as the change in time approaches 0
  • speed: the magnitude of instantaneous velocity vector
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17
Q

What is force and its unit?

A
  • (vector) pushing or pulling on objects
  • can exist between objects that are not touching
  • newton (N) = kgm/s^2
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18
Q

What is gravity?

A
  • an attractive force that is felt by all forms of matter
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19
Q

What are gravitational forces?

A
  • all objects exert gravitational forces on each other
  • usually do not have much significance on a small scale because other forces tend to be much larger in magnitude
    Fg = Gm1m2/r^2
  • if r is halved, Fg is quadrupled
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20
Q

What is friction and its 2 types?

A
  • a type of force that opposes the movement of objects
  • always oppose an object’s motion and cause it to slow down or become stationary
  • static and kinetic
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21
Q

What is the difference between static and kinetic friction?

A
  • static (fs): exists between a stationary object and the surface upon which it rests (0 uk –> need more force to get an object to start sliding than it takes to keep an object sliding
  • fs can have many values depending on magnitude of an applied force, fk is a constant value
22
Q

What is the coefficient of static friction?

A
  • us

- a unitless quantity that is dependent on the two materials in contact

23
Q

What is normal force?

A
  • N = Fg = mg
  • component of the force between 2 objects in contact that is perpendicular to the plane of contact between the object and the surface upon which it rests
24
Q

What is the difference between mass and weight?

A
  • mass: (m - scalar) a measure of a body’s inertia (kg)
  • weight (Fg - vector): a measure of gravitational force on an object’s mass (N)
    Fg = mg –> g = 10 m/s^2
25
Q

What is acceleration?

A
  • the rate of change of velocity that an object experiences as a result of some applied force
  • when no force, a=0 and velocity constant
26
Q

Deceleration?

A

acceleration in the direction opposite the initial velocity

27
Q

What is instantaneous acceleration?

A
  • average acceleration as change in time approaches 0
28
Q

How can acceleration be determined from velocity v time graph?

A
  • the tangent (slope) indicates the instantaneous acceleration
  • +slope = +acceleration and in the same direction as the velocity
29
Q

What is Newton’s first law?

A

Fnet = ma = 0

- an object will remain at rest or move with a constant velocity if there is no net force on the object (inertia)

30
Q

What is Newton’s second law?

A

Fnet = ma

- any acceleration is the result of the sum of the forces acting on the object and its mass

31
Q

What is Newton’s third law?

A

Fab = -Fba

- to every action there is always an opposed by equal reaction

32
Q

What is linear motion and its 4 equations?

A 
- the object's velocity and acceleration are along the line of motion, so the pathway of the moving object continues along a straight line
v = vo + at
x = vot + at^2/2
v^2=vo^2 + 2ax
x = avg v(t)
33
Q

What is free fall?

A
  • falling objects exhibit linear motion with constant acceleration
  • when air resistance is negligible
34
Q

When is maximum height reached?

A

when velocity = 0

35
Q

What is air resistance?

A
  • opposes motion of an object, like friction

- value increases as the speed of the object increases

36
Q

What is drag force?

A
  • an object in free fall will experience a growing drag force as the magnitude of its velocity increases
  • eventually, drag force = in magnitude to the weight of the object and the object will fall with constant velocity (terminal velocity)
37
Q

What assumption can be made about maximum height if air resistance is negligible?

A
  • the amount of time an object takes to get to it maximum height is the same time it takes for the object to fall back down to the starting position
38
Q

What is projectile motions?

A
  • motion that follows a path along 2 dimensions, both x- and y-component
  • assume air resistance negligible
  • only experience force and acceleration of gravity when in the vertical direction (along y axis)
    Vx constant; Vy changes by g
39
Q

In projection motion, when is there only acceleration?

A

in the vertical direction, no the horizontal (x)

40
Q

How do you solve inclined planes problems?

A
  • divide force vectors into components that are parallel and perpendicular to the plane
    Fg(para) = mg sin.theta
    Fg(perp) = mg cos.theta –> normal force
41
Q

What is circular motion?

A
  • occurs when forces cause an object in a circular pathway

- upon completion of one cycle, the displacement of the object is 0

42
Q

What is uniform circular motion?

A
  • the instantaneous velocity vector is always tangent to the circular path
  • object moving in circular path tends to break out of its circular pathway and move in a linear direction along the tangent
  • the tangential force is 0 because there is no change in speed of the object
43
Q

What is centripetal force?

A
  • stops object in circular pathway from moving linearly
  • always points radially inward
    Fc=mv^2/r
44
Q

What is centripetal acceleration?

A
  • acceleration generated by centripetal force that keeps an object in its circular pathway
  • when centripetal force is no longer acting on the object, it will simply exit the circular pathway and assume a path tangential to the circle
45
Q

What are free body diagrams?

A

representations of the forces acting on an object

46
Q

What is translational equilibrium?

A
  • occurs in the absence of any net forces acting on an object (no force means no acceleration which mean constant velocity or 0 velocity)
  • an object in translational equilibrium has a constant velocity and may or may not be in rotational equilibrium
47
Q

What is assumed when objects are in equilibrium?

A
  • net force = 0

- magnitude of T pulling up = Fg pulling down

48
Q

What is translational motion?

A

occurs when forces cause an object to move without any rotation

49
Q

What is rotational motion?

A
  • occurs when forces are applied against an object causing the object to rotate around a fixed pivot point (fulcrum)
50
Q

What is torque?

A
  • application of force at some distance from the fulcrum
  • generates rotational motion because it depends on the magnitude of the force and the length of the lever arm and the angle at which the force is applied
    T = r x F
    = rFsin.angle
  • clockwise (-); counterclockwise (+)
51
Q

What is rotational equilibrium?

A
  • occurs in the absence of any net torques acting on an object
  • rotational motion may consider any pivot point, but the center mass is most common
  • an object in rotational equilibrium has a constant angular velocity (=0)

MCAT Physics + Math (12 decks)

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