Physical Science Test 2
What is the buoyant force acting on a 10-ton ship floating in a fresh-water lake? 10 -tons is the weight of the ship.
10 tons
A 100 kg car accelerates at 3 m/s2. What is the force produced by this acceleration?
300 N
A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is
400 N
If 10 N pull east and 15 N pull west, the net force is
5 N west
A skydiver who weighs 500 N reaches terminal velocity. The air resistance on the skydiver is
500 N
This is ______________- wherever speed is greater, pressure is less.
Bernoulli's Principle
Which of Newton's Laws of Motion states in part, "An object at rest remains at rest" ?
First
Sir Isaac Newton
Jan 4, 1643-1727 scientist professor at universities tough childhood- lost father invented calculus
Newton's First Law is another way of describing
Mechanical Equilibrium
If a 50N person falls at terminal (constant) velocity what is their air resistance force?
Must be 50 because constant velocity is at 0. a=0 net force=0
Lurching forward when the brakes are applied to a moving car is an example of
Newton's First Law
Applying twice as much force to cause twice as much acceleration to an object is an example of
Newton's Second Law
Understanding that when a bat hits a ball there is an equal force exerted by the ball on the bat is an example of
Newton's Third Law
heavy person and light person have same size parachute. jump at the same time and height. Do they fall at the same rate (acceleration)?
No because of the parachute. different acceleration and terminal velocity. the heavy person will reach the ground first. The lighter person doesn't require as much air resistance.
Which of Newton's Laws of Motion states, "A net force produces an acceleration in the same direction as the net force, proportional to the net force, and inversely proportional to the mass" ?
Second Law
"When one object exerts a force on another object, the second exerts an equal but opposite force on the first" describes Newton's _____Law.
Third
The buoyant force on a floating object is equal to the weight of the object, and also equal to the weight of the fluid displaced by the object.
True
Describe how the video of Felix Baumgartners high altitude jump incorporates ideas from chapter 2 and chapter 5. What are some of these ideas (give at least 2 from each chapter)?
Two concepts we covered in chapter 2 that describe Felix's jump includes Newton's 2nd Law: free falling and falling with air resistance. Baumgartner initially fell by free falling due to the fact that we so high in the atmosphere there was no air resistance to slow him down. Newton confirmed that Galileo's idea of when objects free fall they fall at 10 m/s^2. So Felix continuously sped up 10 m/s^2 from the time he jumped until he reached a part of the atmosphere where there was air resistance. Newton's 2nd law talks about the net force being proportional to acceleration. Once he reached air resistance, the air resistance kept increasing and the net force and acceleration decreased allowing him to eventually come to gradual landing. In chapter 5, two concepts we covered that go along with Felix's jump are atmospheric pressure and density. We know there is more pressure the deeper one goes. Pressure is to due to the weight of air above, so the higher you go the less air there is to weigh it down; therefore, less pressure. So when Felix was taken up to the edge of outer space there was not enough pressure and oxygen; therefore, he had to wear a mask that allowed him to breathe. Once he got closer to land the pressure increased allowing him to breath easier. The same fact goes for density. The air is less dense the closer one gets to outer space. This is why people get altitude sickness when they climb high mountains because there is not as much oxygen, and one could possibly die from it.
Comparing a heavy parachutist and a light weight parachutist, the heavy parachutist falls with ________ terminal velocity.
a higher
acceleration formula
a=net force/mass
When you stand at rest on a pair of bathroom scales, the readings on the scales will always ____________ no matter how you shift your weight between them
add to equal your weight
An umbrella tends to jerk upward on a windy day principally because
air pressure is reduced over the curved top surface.
Mass is
all of these are correct when used together: the same everywhere, a measure of an object's inertia, the amount of matter in an object.
The resistive force of friction occurs for
all of these are correct: solids, liquids, gases
A fluid
all of these: is able to flow, exerts pressure, is a liquid or a gas
The air in this room has
all of these: volume, density, pressure
displacement rule
an object submerged in a fluid displaces a volume of fluid equal to its own volume
Archimedes principle
an object that is partly or fully submerged in a fluid is buoyed up by a buoyant force equal to the weight of the fluid displaced by the object.
Objects in free fall hit the ground ___ when dropped from the same height
at the same time
A swimmer cannot snorkel more than a meter deep because air
at the surface will not freely enter the higher-pressure region in the compressed lungs.
equilibrium
balanced forces
Newton's theory of motion
based on Galileo's work but more developed
As a helium-filled balloon rises in the air, it becomes
bigger in volume
more pressure on the _____
bottom
The ___________ on a floating object is equal to the weight of the object, and also equal to the weight of the fluid displaced by the object.
buoyant force
What makes an object float in a liquid?
buoyant force is equal to weight of the object
The Bernoulli effect causes passing ships to be drawn together when the ships are
close together, creating a narrow channel.
buoyant force > weight net force & example
could rise net force = increasing bubble in air or water
buoyant force < weight net force & example
could sink net force = decreasing rock sinking in water or air filled balloon
Why do people pass out with low blood pressure?
cutting oxygen off. If someone passes out put their feet above their head so the pressure can go towards their head.
As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe
decreases
The acceleration of an object falling with air resistance
decreases
When an object falls downward and has air resistance acting on it, the net force
decreases
Water pressure at the bottom of the lake depends on the
depth of the lake
we can increase the buoyant force on objects making them ______
displace more fluid (increase objects volume and decreased object's density.
A given net force propels an object along a straight-line path. If the net force were doubled, its acceleration would
double
An object at rest or an object in constant velocity motion remain that way
due to their inertia
In the plasma lab, the force at work was the
electric force
When a bug hits the windshield with 5 N of force, the windshield hits the bug back with _____ force
exactly 5 N of
Bernoulli's Principle: curved surfaces, like an umbrella, have_______ air flow so _______ pressure.
faster; lower
Bernoulli's principle: narrow channels create ________ flow with _______ pressure.
faster; lower
everything falls at the same rate during
free fall
The acceleration of an object in free fall is
g
Lobsters live on the bottom of the ocean. Compared with the density of seawater, the density of a lobster is
greater
Wind blowing over the top of a hill
has lower pressure than air that is stationary
buoyant force = weight
hovering net force= 0 fish, bubble, balloon
If an object submerged in a fluid is in equilibrium, it could be
hovering in mid air
The net force on an object moving at a constant 30 m/s in a straight line is
is zero
Whenever the net force on an object is zero, its acceleration
is zero
What happens to the speed of an object in free fall?
it increases 10 m/s^2
Newton's Second Law
law of acceleration the acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction of the net force, and is inversely proportional to the mass of the object.
Newton's first law of Motion
law of inertia every object continues in a state of rest or constant velocity motion (at the same speed in a straight line) unless acted upon by a nonzero net force.
If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is
less
In a styrofoam cup, if you were to poke three holes the top would_____, the middle would______, the bottom would______
less pressure, more than the top but less than the bottom, the most pressure.
Fast flow has _______ pressure.
low
Bernoulli's principle- fast air over curves has ______ pressure.
lower
denser fluids weigh _____
more
Airplane lift is achieved when air pressure on the bottom of a wing is
more than on the top, creating an upward buoyant force
When comparing two liquids, the one with the greatest density will exert the most ___________ on an object
pressure
When an object falls downward in free fall, the net force
remains constant
If the buoyant force is greater than the weight of an object, the object would possibly be
rising
Consider two tubes filled with water at the same height, one with fresh water and the other tube with salt water. The pressure is greater at the bottom of the tube with
salt water
same depth no matter the size of the container equals
same pressure
Air resistance, or drag, is primarily influenced by
speed and surface area
Your weight is
the gravitational attraction between you and the earth.
Buoyant force acts upward on a submerged object because
the net pressure exerted by the fluid is upward.
The reaction force to weight is
the object pulling up on the earth.
When you push a crate across a level floor at constant velocity, friction between the crate and the floor is
the same amount as your pushing force.
Compared to the buoyant force on you when floating in fresh water, buoyant force on you when floating in the dense water of the Dead Sea is
the same!
If the buoyant force is greater than the weight of an object, the net force on the object would be
upwards
If a gas is compressed, its
volume decreases
An object completely submerged in a fluid always displaces its own
volume of fluid
Air pressure can't push down into the lungs because the lungs are under pressure from the ______.
water
A dam is thicker at the bottom than at the top because
water pressure is largest at higher depth
A rising balloon is buoyed up with a force equal to the
weight of air it displaces
Atmospheric pressure is caused by the
weight of the atmosphere pressing down on us.
If the buoyant force is equal to the weight of an object, the net force on the object would be
zero