Physics 1
atmospheric pressure- force per unit area exerted on a surface by the ... fluid pressure- force per unit area exerted on a surface by the ... gauge pressure- force per unit area exerted on a surface by the ...
weight of air above that surface in the atmosphere of Earth weight of a column of liquid relative to local or ambient pressure
Which is the y component? Which is the x component?
V *Sin theta v=magnitude of original vector V *Cos theta v=magnitude of original vector
final or initial velocity only, given drop height
V = √(2gh) or V = √(2ax)
FORCES are ___ and can thus sum to zero (no net force) Force is measured in Newtons -What is the units of Newton
VECTORS FORCES ARE VECTORS Kg * m/s^2
Acceleration is any change in ___ Acceleration = how quickly the __ is __. Not the MAGNITUDE of the __ ITSELF
VELOCITY velocity ; changing velocity
Vavg
Vavg=(V1+V2)/2
Maximum Static Friction: In cases of static friction, the friction created before an object begins to slide will always remain equal to the net applied force which the friction is opposing. For example, if you push on a boulder with 20 N of force, there will be __ N of static frictional force opposing you. If you increase the force you apply to 100 N, the static friction will increase to __. This continues up to the "maximum static friction." Once this value is exceeded, the object will begin to slide and we then have a case of kinetic friction, NOT static.
20 100N
Archimede's principle definition
Any object displaces an amount of fluid exactly equal to its own volume (submerged) or to the volume of whatever fraction of the object is submerged (floating) the buoyant force = weight of displaced water/liquid
Simple Harmonic Motion (SHM):
Anything that oscillates back and forth, and can be represented by a sine wave graphically (sine graph: goes thru 0)
Apparent Weight (AW) of a submerged object:
Apparent Weight (AW) = Actual Weight (aW) - Buoyant Force (Fbuoyant) Useful because the difference in actual weight and apparent weight will tell you 1) the Fb and 2) the weight of that volume of liquid
Turbulence
At low velocity, fluids flow laminarly, but as velocity increases (especially for non-viscous fluids) fluids become turbulent - meaning that the net flow is still in one direction but there are random eddies, changes in direction, changes in velocity, and so forth.
What is the difference between distance and displacement?
Distance is a scalar quantity which tells you "how much ground was covered" Displacement is a vector which tells you "how out of place an object is" -SHORTEST DISTANCE b/t point A and B
Distance/Displacement vs. time of a car going around a track.
Distance would then be an increasing linear line.
Force DUE TO GRAVITY formula
F = Gm1m2/r2 gives the force due to gravity NOT gravity itself. Gravity itself, usually called "gravity," "the strength of the gravitational field," or "acceleration due to gravity" is represented by a lowercase g and is described by the formula: g = Gm/r2 .
Hooke's Law: Springs, and many other items such as resilient solids, rubber, and even bonds between atoms, follow Hooke's Law. F is the restoring force
F = k∆x (where ∆x is the displacement of the spring from its equilibrium point, NOT the overall length of the spring)
Describe the forces present on an inclined plane.
F=mgsin (force down the plane, parallel to surface) Fn= mgcos Vf=√(2gh) (velocity at the base of an incline a= g sin (absence of friction or other forces) F fric(k or s)= u Fn (mgcos o) (up the plane)
A student hangs a 4 kg mass on a spring and it stretches 1 m. What is the spring constant, and how far will the spring stretch if he attaches a 2 kg mass?
FIRST: Use F = mg to convert that mass into a force NEXT: Use F = k∆x -plug in found F and find k 40N/m and will stretch a 2 kg mass .5 meters
Static Friction formula
Fs = μsmg cos(theta) or
Gravity Definition What is a Field?
Gravity is a field that exists between any two objects with mass. an invisible influence capable of EXERTING A FORCE on a mass or charge.
Conservation of energy with a mass with velocity v hitting a spring. KE and PE relationship
Initial KE = Final PE
THINK OF FORCE AS: Force = __ __ capable of ... Is torque a force?
any influence capable of causing a mass to ACCELERATE yes torque is a force
What causes Friction on a microscopic level? Molecular?
Microscopic- At points of contact between the two objects, there is actual covalent/ionic bonding that is occurring. These bonds need force to be broken so the object continues to move. Molecular- When two objects are pressed together, this causes intermolecular attractive forces between the two surfaces Ffric=mew*Fn
Describe two skydivers jumping from a plane, one of mass 100kg, and one of mass 150kg.
More mass will take longer to reach terminal velocity (Fair=mg) This means it will accelerate longer and hit the ground with more velocity
Fluid pressure formula (in Pascals)
P = pgh The weight of the column of fluid above the point of measurement. (h is depth, not height)
Elastic Potential Energy: Potential Energy stored in a compressed spring =
PE = (1/2) k∆x^2
PE (in space or not assuming g=10m/s^2) Why do we include a negative sign in the previous equation?
PE = -Gm1m2/r With increasing r, PE becomes less negative which means an increase in PE.
Gravitational Potential Energy: PE = formula
PE = mgh (near earth) Anything with mass can have gravitational potential energy.
Pendulum KE and PE
PE is max at top (min at bottom) KE is max at bottom (min at top)
pressure formula and units
Pressure = force/ area force(N) / area (m2) N/m2 = pascal
Friction opposes...
SLIDING, not motion
Vector * Scalar rules Vector + Scalar Rules
Scalar * Scalar = Scalar Vector * Scalar = Vector Vector * Vector = Scalar Vector + Vector = Vector Vector + Scalar = Vector Scalar + Scalar = Scalar vector will always win except vector x vector which = scalar
What is the difference between speed and velocity?
Speed is SCALAR and refers to "how fast an object is moving" or the rate at which an object covers a distance. Velocity is a VECTOR and is "the rate at which an object changes their position".
Definition of Hooke's law
States that the extension of a spring is in direct proportion with the load applied to it. Or, Stress is directly proportional to strain.
Max Static F: 500N is applied to an object and it does not move. 501N is applied and it just begins to slide. Describe the force that must be applied in order to continually move the object.
Static friction force- the MIN. amount of force required to BEGIN sliding OR the MAX amount of force that can be applied BEFORE it moves. Kinetic friction force- the MIN amount of force required to KEEP an object SLIDING 501 is static friction and something less is kinetic
What causes buoyancy force? How does it change with depth?
The reactionary force caused by the object displacing water by its weight (mg). Does not change much unless the volume of water displaced by the object changes and it may increases.
Tension = acceleration impact
Tension is the force in a rope, string, cable, etc. In most cases, you can ignore tension by replacing it with a force vector on the object to which the rope, string, or cable is attached. 1)No acceleration and the object is in equilibrium or 2) There is a net force and therefore acceleration.
When a block is at rest it is in __. The forces up the plane due to friction (given in this case by F = micro mgcos theta), must __the forces down the plane (F = mgsin theta). When the maximum frictional force just balances the downward force, micro mgcostheta = mgsin theta. Increasing the mass impacts both sides of the equation __and therefore the block remains at __. Answer B is incorrect because increasing the incline will make the right side of the equation increase and the left side decrease. Answer C is incorrect because it will decrease the left side only and the block will slide.
equilibrium equal equally rest
Kinetic Friction formula
fk=μkN or Fk = μkmg cos(theta)
acceleration due to gravity formula
g = Gm/r2 (10m/s^2 usually)
Pressure is a constant at any vertical depth within the same fluid what does this mean for pressure in tank and pipe?
if a pipe exits horizontally from an enormous 1,000-meter-tall water storage tank, the fluid pressure inside that pipe is the same as the fluid pressure inside the tank at that same vertical distance below the surface of the fluid
Application of the Bernoulli equation: if fluid velocity increases
if fluid velocity increases, pressure decreases BOTH GASES AND LIQUIDS act as FLUIDS on MCAT
frequency is the __ of a period
inverse
If there's sliding, it's ___ friction; if there's no sliding, it's ___ friction
kinetic static
gravity acceleration illustrates what ... If a ball is going up, it... If a ball is going down, it..
loses 10 m/s of velocity each sec. gains 10 m/s of velocity each sec.
Tension = mg + ___
ma
vectors have ___&____ scalars have just __
magnitude and direction magnitude
At terminal velocity, EQUATION At terminal velocity, the object has stopped accelerating; the forces of gravity and air resistance are now balanced.
mg = F air
distance = rate x __ Can u use this formula to calc displacement?
time No, Rate *time will be a scalar quantity and displacement is a vector
Convert between pascals, mmHg, atm, and torr 1 atm = __ mmHg 1 atm = __ torr 1 atm = __ kPa 1 torr = __ mmHg
1 atm = 760 mmHg 1 atm = 760 torr 1 atm = 101.3 kPa 1 torr = 1 mmHg
How do you add vectors components?
(Ax + B)^2 + Ay^2= C^2
Buoyancy force equation and what it means
p- density of fluid, NOT object v- volume of fluid that is displaced, not total volume g- 10m/s2 Fbuoyant = pvg
Center of mass -conceptually -formula Center of gravity is located where?
-a weighted average of mass distribution of mult. objects -r = displacement vector b/t a reference pt. and each mass -r1m1 +r2m2 +r3m3.../mtotal at the center of mass
What is the ration of two forces where mass is A=2B? Acceleration? What force does the Earth experience due to a falling rock?
1) 1:1 but B will have an acceleration 2x as great. 2) The earth feels a pull from the rock with a force equal to the earth on the rock.
Air resistance is the force exerted on projectiles or falling bodies due to actual physical collisions with air molecules. how do these factors affect the magnitude of air resistance? 1) Cross-sectional Area: 2) Shape: 3) Velocity: Always assume air resistance is being ignored, unless it specifically states otherwise in the question stem or passage.
1) Greater Surface Area= More A.R 2) Less Aerodynamic= More A.R 3) Greater Velocity= More A.R
Density of water: 1000 kg/m3 or 1 cm3 = 1 L of water = 1 mL of water =
1.0 g/cm3 1 mL 1 kg 1 g
True or false? a ball moving with twice the kinetic energy will compress a spring twice as much. 3 times the velocity will compress a spring 3x as far.
1/2 mv^2 = (1/2) k∆x^2 False (actually compress it squrt2 as much) True
Newton's First Law (Law of Inertia)
A body at rest tends to stay at rest and a body in motion tends to stay in motion at the same speed and direction unless acted upon by an unbalanced force
Capillary action: Cohesive vs Adhesive forces
Cohesive-Cohesive forces are the intermolecular forces which cause a tendency in liquids to resist separation. These attractive forces exist between molecules of the SAME substance. Adhesive- the attractive forces between unlike molecules.
Newtons third law states
ACTION-REACTION Whenever one object exerts a force (action) on another object, that other object exerts an equal & opp. force (reaction) onto the first object
Surface Tension: The intensity of intermolecular forces, per unit length, at the surface of a liquid. (why does a whole pin float but not a piece of it?)
Because there is less surface area of water (less intermolecular forces) to act on the small piece so that it breaks through the forces easily.
How does capillary action work?
Capillary action only occurs when the adhesive forces are stronger than the cohesive forces, which invariably becomes surface tension, in the liquid.
Fluid Flow in Cardiovascular System equation:
Cardiac output = stroke volume x heart rate variable A is the cross-sectional area of the blood or lymph vessel, and V is velocity
Density:
D = m/v
Laminar Flow
Fastest flows in the exact center and slowest towards the edge of the pipes. And rest of fluid flows in concentric sheets (each w/ diff velocities)
relationship Q = AV to explain how velocity varies as blood flows throughout the human circulatory system
Flow rate remains constant so as area decreases velocity increases. aorta → arteries → arterioles → capillaries → venules → veins → vena cava
Newton's second law
Fnet=ma Fnet is the vector sum of all forces acting on the object.
a smaller vertical velocity and greater horizontal comp. of velocity (due to a greater angle 50degrees) will mean that the projectile motion ball will have __TIME in the AIR
LESS
When you see projectile motion, THINK: 1) Horizontal velocity __ changes (as long as you are ignoring air resistance) 2) Horizontal acceleration always = __ 3) Vertical acceleration always = __ m/s2 downward 4) Vertical behavior is exactly __ (i.e., if ignoring air resistance, a projectile's upward trip is identical to its downward trip) 5) Time in the air depends on the __ component of velocity only 6) Range depends on both the vertical and horizontal components of velocity 7) __ is always the same for both the x and y components of the motion.
NEVER 0 10 symmetrical vertical Time
When you see "Constant Velocity" or "Constant Speed" what do you think?
NO ACCELERATION NO NET FORCE ALL forces sum to ZERO -ex: up forces = down forces ; left forces = right forces NO CHANGE in DIRECTION The object is in EQUILIBRIUM
Can you accelerate a ball horizontally across a room? Vertically?
No, In order to accelerate it must 1) be in contact with the object creating the force or 2) be under a field force at that exact moment. Ex. A ball being thrown horizontally has no vertical component so has no acceleration due to grav. Its velocity also cannot go negative (back to the left) -It's only accelerating horizontally during brief time ball contact w/ object creating horizontal force: hand -It is accelerating vertically because it is under the influence of a gravitational field.
D=rate*time for displacement?
No, rate and time are both scalar quantities and tell us nothing about direction whereas displacement is a vector so we need information about direction.
Flow rate
Q = AV Area is always the TOTAL cross-section area. Therefore, if a large pipe splits into 2 smaller pipes, you must add the cross-sections of both new pipes to get the new area.
Steps for Interpreting Linear Motion Graphs: What does slope ___? Is slope + or -? Is slope constant (__ line) or non-constant (__ line)? What value is on the y-axis? This quantity is __ Is the y value (+) or (-) (i.e., is the line above or below the x-axis?). What does this observation tell you? Do you expect the value on the y-axis to be large or small at the beginning?
REPRESENT -displacement vs time graph: slope = velocity -velocity vs time: Slope = acceleration -if SLOPE is STRAIGHT, slope is NOT INCREASING (it's CONSTANT) straight ; curved a straight line on a displacement vs. time graph tells us that velocity is constant and therefore the object is in equilibrium CHANGING -If we see a flat line with zero slope, this means that whatever is on the y-axis is constant
Projectile Motion: Think of projectile motion as nothing more than falling body problems in two dimensions Immediately resolve the given vectors into components; then solve in your head as you would any other motion problem. "Range," or horizontal distance traveled, is a new value asked for in projectile motion. It is the product of velocity in the x-direction (Vx) and time (t).
Range formula: Range = Vx (t) = horizontal distance traveled
How do you add vectors head to tail?
Then A^2 + B^2 =C^2
Ideal, Non-Viscous Flow: This is how ideal, non-viscous fluids flow
There is assumed to be no friction (drag) between the fluid and the walls of the pipe, or between fluid molecules themselves. ASSUMED ON MCAT. Fluid near the WALL of the pipe flows with the SAME VELOCITY AS FLUID AT CENTER OF PIPE
What is the tension of a rope being pulled by 50 N on both sides?
There is no tension.
Poiseiulle Flow
This is how Real, Viscous fluids flow. Laminar (see below)
x is distance a is acceleration t is time
X = (½)at^2
What is Specific Gravity?
a ratio that describes how DENSE something is compared to water.
As the angle of incline of a plane increases, what happens to the value of a, sin and cos? What happens to the normal force and to the force down the plane? What are the minimum and maximum for acceleration down a plane?
a will increase and approach 10 m/s^2 Sin o will increase and Cos o will decrease Normal force will decrease Force down the plane will increase approaching mg Min is 0 m/s^2 and Max is 10 m/s^2
Bernoulli's Equation demonstrates the law of ...
conservation of energy K = P + pgh + (½)pv 2 P - Pressure Energy, pgh - PE per volume of fluid (h is height), 1/2pv^2 - Kinetic energy of moving fluid molecules. The sum of these three is always constant (K)
Why is each scalar: mass, temperature, speed, work, energy, charge, time, and density?
a) mass can be measured with a scale b) temperature does not show direction c) speed is usually a number d) Work is two vectors multiplied together (f*d) e) Energy has no direction and it is a scalar*scalar f) charge also has not direction g) time is measured in months, days, years h) density is m/v which are both scalar
Why is each a vector: velocity, displacement, acceleration, force, weight, electric and magnetic field, momentum, impulse, and torque?
a) velocity is change of displacement per time b) displacement is change of distance c) acceleration is change in velocity per timed) force is m*a and a includes a change (deltaV) e) weight=mg and g is a vector quantity because (a=deltaV/t) f) magnetic fields describe force between electric currents g) electric field is the force experienced by an electric charge h) momentum is p=mv and v is a vector quantity I) Impulse is the change in momentum J) torque is force*distance and force is a vector quantity
Why does the displacement of the pendulum gradually decrease over time?
acceleration is always in the opposite direction of the velocity and there will reach a point where the "deacceleration" overcomes.
Pascal's Law: Pressure is transmitted in ... Put another way, if pressure increases at any point in a confined, incompressible fluid, it ...
all directions, undiminished, through a contained, incompressible fluid. increases by that same amount at every other point within that fluid.
Cbuoyancy=
at the center of mass of the fluid displaced by the submerged object (not the submerged object itself)
A constant force WILL
cause an object to MOVE faster and faster due to constant acceleration and LINEARLY INCREASING VELOCITY
Because g is inversely related to r, as the object approaches the earth the rate of velocity change will ___
increase
PE (fluid)
pgh (p is density which is mass/volume)
distance = rate x time what is rate?
rate = avg velocity
What do you multiply by if your product is vector? What do you multiply by if your product is scalar?
sin(theta) cos(theta)
total time in the air. The variable V must be the vertical component of initial velocity
tair= 2V/g
INERIA = MASS = measure of an object's __
the ability of an object to RESIST A CHANGE to its VELOCITY measure of an object's INERTIA
What about objects floating in liquid?
the fraction of the object submerged = the ratio of the density of the object to the density of the liquid. (unless water, then the fraction submerged equals the SG)
A constant force WILL NOT cause an object ...
to go faster and faster but it will cause a constant (not changing) ACCELERATION a constant force will create CONSTANT ACCELERATION- and hence, a CHANGING VELOCITY
