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