Elementary Physics 1310 Exam 3 Xiao
mixture
no chemical bonding between atoms. ex: the atmosphere
strength/weight
inversely proportional to area/size
increases
when a fluid goes to a narrower region, speed...
weight of object
1 object in different liquids. if floating, Fb=?
density of fluid
1 object in different liquids. if submerged, Fb=?
same
10 kg aluminum, 3 kg aluminum. which is more dense?
maximum height you can suck a straw
10.3m However strong your lungs may be, or whatever device you use to make a vacuum in the straw, at sea level the water could not be pushed up by the atmosphere higher than 10.3 m.
weight of heavier object
2 objects floating in the same liquid. if both floating, Fb=?
V=Fb because density of liquid is the same
2 objects in the same liquid. if both submerged, V=? why?
molecules
2 or more atoms of same or different elements. ex: CO, H2 DIFFERENT THAN ATOMS
compound
2 or more different types of atoms. ex: CO (carbon monoxide)
ears pop
A change in altitude means a change in air pressure, and this causes a temporary imbalance in the pressures on the two sides of your eardrum.
component combination of projectile motion
A combination of a horizontal constant velocity motion and a vertical free fall motion.
decreases
A fish normally has the same density as water. A fish can regulate its density by expanding and contracting an air sac in its body that changes its volume. When a fish expands its air bladder, the density of the fish...
5 meters
A girl throws a ball horizontally off the edge of a cliff. As the ball leaves the girl's hand, 1 second later it will have fallen (use equation d= 1/2gt^2) (distance=1/2[gravity][time^2]) d=1/2[10][1]^2
1/3 the original pressure
A piston in an airtight pump is withdrawn so that the volume of the air chamber is increased 3 times. What is the change in pressure?
equally spaced
A projectile is launched horizontally are the HORIZONTAL positions equally spaced or farther apart with time?
farther apart
A projectile is launched horizontally, are the VERTICAL positions equally spaced or farther apart with time?
more
When you stand on one foot instead of two, the PRESSURE you exert on the floor is
atmosphere
Air is more compressed at sea level than at higher altitudes. Compromise between energetic molecules that tend to fly away and gravity that holds them back near Earth. We live at the bottom of an ocean of air
projectile motion
Any object that moves along a curved path under the influence of gravity.
same height
Consider two mercury barometers, one with twice the cross-sectional area of the other. Compared with the wider tube, mercury in the smaller tube will rise
Curvature of Earth (fast moving projectiles) Satellites
Earth surface drops a vertical distance of 5 meters for every 8000 meters tangent to the surface -speed is 8km/s=29,000km/h
floating
Fbuoyant = Wobject if....
buoyant force is pressure times volume times gravity
Fbuoyant=Wfluid=(Pfluid)(Vfluid)(g)
principle of continuity
For continuous flow, a fluid speeds up when it goes from a wider to a narrower region, and slows when it goes from a narrower to a wider region.
orbital speed is less
For higher altitudes in orbit, is the speed less or higher? (orbital speed of the moon?)
buoyancy in air
Gas-filled balloon Helium, hot air As balloon rises, atmosphere becomes less dense with altitude, it continues to rise until FB = Wair = Wballoon or ρair = ρballoon.
2, buoyancy and gravity
How many forces act on a submerged body in a fluid?
same at any depth
If an object is fully immersed in a liquid what is the force on the object at each depth?
lower
If the barometer is moved from the sea level to the top of a mountain, will the height of the mercury column change?
500 N
If the pressure in a hydraulic press is increased by an additional 10 N/cm2, how much extra load will the output piston support if its cross-sectional area is 50 cm2?
vertical and horizontal components of motion
In a horizontal projectile what is the component combination of the curvature path?
atom characteristics
Incredibly tiny Numerous Perpetually in motion Ageless
60 degrees (subtract the angle from 90)
Neglecting air drag, a ball tossed at an angle of 30° with the horizontal will go as far downrange as one that is tossed at the same speed at an angle of?
atmospheric pressure
Not uniform (altitude, locality, weather) At sea level, the average atmospheric pressure is 1 atm = 101.3kPa, 1 Pa = 1 N/m2.
correct
On a boat ride, the skipper gives you a life preserver filled with lead pellets. When he sees the skeptical look on your face, he says that you'll experience a greater buoyant force if you fall overboard than your friend who wears Styrofoam-filled preservers. correct or incorrect?
increase in depth = increase in pressure
Pressure of liquid = pressure at surface + pgd
pressure in liquid
Pressure pushes the water sideways, out of the holes. The greater the depth, the greater the exiting speed.
brownian motion
Robert Brown observed collisions between visible particles and invisible atoms
Ranges of a projectile launched at an angle
Same range is obtained from two different launching angles when the angles add up to 90 °(if D = 0). -Maximum range occurs for ideal launch at 45 °.
amorphous solids
Solids that do not have atoms arranged in a regular array. Ex. rubber, glass, plastics -Atoms vibrate in random arrangement
near the middle
Suppose you drill a hole horizontally through a tree branch. Where will the hole weaken the branch the least?
Remains the same
The velocity of a typical projectile can be represented by horizontal and vertical components. Assuming negligible air resistance, the horizontal component along the path of the projectile
same
When you stand on one foot instead of two, the FORCE you exert on the floor is
parabola
Trajectory of a projectile.
same
Two solid blocks of identical size are submerged in water. One block is lead and the other is aluminum. Upon which is the buoyant force greater?
submerged
Vfluid=Vobject if...
floating
Vfluid=Vsubmerged part if...
taller
Water pressure provided by a water tower is greater if the tower is...
increases
When a fish makes itself less dense, the buoyant force on it
straight line path
When a projectile is launched at an angle, with no gravity, what path will the object travel?
increases
When a submarine takes water into its ballast tanks, its density
decreases
When a submerged submarine expels water from its ballast tanks, its density
Bernoulli's principle
Where the speed of a fluid increases, the internal pressure decreases. *applies to smooth steady flow of constant density fluid only
barometer would be too tall
Why don't barometers use water instead of mercury?
salt water
Will ship float higher in saltwater (density = 1.03 x 103 kg/m3) or in freshwater (density = 1.00 x 103 kg/m3)?
the same as the time for it to return to its initial level
Without air resistance, what is the time for a projectile to reach maximum height and time to return to its initial level?
Satellites remain in orbit instead of falling to Earth
Without gravity, it would move in a straight line. The gravity at this height is only a few percent weaker than it is at Earth's surface.
satellite
a free falling object around earth
Archimedes' principle
an immersed object is buoyed up by a force equal to the weight of the fluid it displaces.
bigger
as pressure decreases, bubbles get...
where satellites are positioned
beyond Earth's atmosphere, where air resistance is almost totally absent.
pressure inside car is greater than outside
canvas top of convertible car puffs up as car moves because..
vertical component
component that changes during projectile motion. acceleration=10 m/s^2 (gravity)
horizontal component
component that stays the same EVERYWHERE during projectile motion. constant velocity
falling distance
d=1/2gt^2 distance is beneath the path of the projectile, not the initial position
float
density of the object is less than the density of the fluid. float or sink? Pobj < Pfluid
sink
density of the object is more than the density of the fluid. float or sink? Pobj > Pfluid
range
distance covered horizontally by a projectile. dependent on launching speed and launching angle
pressure is the same, force is higher
for a large piston in a hydraulic press, what is the pressure and force compared to a smaller piston?
hooke's law
force is proportional to the change in spring stretch F~Δx (2F~2Δx)
pressure
force per unit area on which the force is exerted p=F/A
independent
horizontal component is independent or dependent of vertical component?
range equation
if 2 projectiles' speed is the same and launch angles equal 90º, range of each is the same (air resistance is negligible)
directly
in Pascal's Principle, area is ? proportional to force
directly
in a barometer, atmospheric pressure is ? proportional to the height.
Pascal's Principle
in a hydraulic press, the pressure at both pistons is the same, but the force is proportional to the area of the piston.
inversely
in boyle's law, volume is ? proportional to pressure
fixed
in one material, density is...
density
measurement of the compactness of matter does not depend on mass P=m/v
hydrogen
most abundant and lightest element
oxygen, carbon, hydrogen, nitrogen, calcium
most abundant in all living things
neutral layer
neither stretched nor squished, part of the object stays the same.
buoyant force
net upward force that a fluid exerts on an immersed object. Force vectors on the sides cancel one another. The upward pressure on the deeper bottom is greater than the downward pressure on the top.
atomic structure
nucleus = protons (+) and neutrons (neutral). concentration of nearly all mass surrounding cloud of electrons (-) less massive
element
one type of atom ex: Hydrogen, Helium, Sodium
weight of displaced fluid = weight of object
place an object in a container that's full of water and weigh displaced water. if the object is floating...
volume of displaced fluid = volume of object
place an object in a container that's full of water and weigh displaced water. if the object is sinking...
independent
pressure is ? of the volume (amount) of the liquid
inversely
pressure is ? proportional to area
directly
pressure is ? proportional to force
boyle's law
pressure is proportional to temperature / volume
strength
proportional to cross sectional area, proportional to area squared ? ~ Ac ~ a^2
weight
proportional to volume, proportional to area cubed ? ~ v ~ a^3
Vertical distance beneath any point = distance covered by the object
relationship between the vertical distance that an object falls beneath the dashed line and distance covered by a free falling object dropped from rest for the same amount of time
speed of satellite is zero
satellite falls straight towards earth
crystalline solids
solids with atoms arranged in a regular array, 3D orderly arrangement. Ex. metals, salts, most minerals -The atoms in solids vibrate in place rather than move about.
compression
squished part of an object gets shorter and wider
tension
stretched part of an object gets longer and thinner
p
symbol for density
atomic number
the amount of protons in the nucleus
decreases
when a fluid goes to a wider region, speed...
increases
when mass increases, density?
decreases
when volume increases, density... (indirectly proportional)
elasticity
when you exert force on an object, the object can return to its original shape
increases
when you squeeze bread, density?
stays the same
when you squeeze bread, mass?
decreases
when you squeeze bread, volume?
steel
which is more elastic, steel or rubber?
streamlines smaller, pressure outside smaller than inside
wind blowing across peaked roof can lift roof off house because...
