AI Physics301 Final

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Distinguish between distance and displacement. Provide one example. 

Distance is the total length of the path travelled. It does not reference changes in direction, just the total distance travelled. If a car were driving straight for 4 miles, and then made a U-turn and drove another 4 miles in the other direction, the distance would be 8 miles travelled. Displacement measures the difference between the starting position and the ending position, and does take change in direction into consideration. Using the same scenario with the car making a U-turn, the distance would be 8 miles travelled, but the displacement would be 0 miles. That is because the car has returned to it's starting position, and there is no distance between start and finishing position. 

If car A passes car B, then car A must be:

moving faster than car B, but not necessarily accelerating

A fullback is running down the football field in a straight line. he starts at the 0-yard line at 0 seconds. At 1 second, he is on the 10-yard line; at 2 seconds, he is on the 20-yard line; at 3 seconds he is on the 30-yard line. This is evidence that...

he is moving with a constant speed

Describe what happens to the position, velocity and acceleration of a baseball dropped off a tall building. 

The position of the baseball will change as its distance from the top of the building increases as it falls. The distance from the ground will decrease as it falls as well. The velocity of the baseball will increase, due to gravity. Free falling objects increase their speed at a rate of 10 meters per second per second, at a constant rate of acceleration.

Which of the following statements is NOT true of a free falling object?

falls with a constant speed of -10 m/s

The average speed of an object which moves 10 km in 20 min is:

30 km/hr

Ten seconds after being dropped from rest, a free falling object will be moving with a speed of...

about 100 m/s

A baseball pitcher delivers a fast ball. During the throw, the speed of the ball increases from 0 to 30 m/s in .1 seconds. The acceleration of the baseball is _______ m/s/s.

300.00

What is the equation for finding velocity with distance and time?

v= d/t

Describe the quantities measured in kinematics?

velocity, distance/displacement, acceleration

What is the equation to find acceleration?

acceleration= (final velocity - initial velocity)/ time

What unit is acceleration measured in?

m/s/s or m/s²

Define force.

A quantitative measure of the push or pull applied to a mass to accelerate it. It has both direction and magnitude.

What is the equation for force?

force = mass x acceleration

Define pressure.

A quantitative measure of the push or pull applied to a particular area. Involving only magnitude.

What is the equation to find pressure?

pressure = force/area

Briefly summarize Newton’s first law of motion.

Inertia. An object in motion will remain in motion unless acted on by an outside force.

Briefly summarize Newton’s second law of motion.

The net force on an object is equal to the rate of change of its linear momentum. F=ma

Briefly summarize Newton’s third law of motion.

Every force has an equal and opposite reaction.

What is a collision?

An interaction between two or more objects

List and define the two types of collisions.

• Inelastic: the net momentum is the same before and after collision, but kinetic energy is lost (jello splat; car crash resulting in a dead stop bc momentums cancel out; bouncy ball not bouncing as high)

• Elastic: complete transfer of momentum, no kinetic energy is lost (two balls collide, complete transfer of momentum)

Explain the Law of Conservation of Energy

Energy can neither be created or destroyed.

Explain the Law of Conservation of Linear Momentum

The momentum before a collision must be equal to the momentum after a collision.

Describe potential energy

The energy which is stored

Describe kinetic energy

The energy which is released in the form of motion

A 5.2 N force is applied to a 1.05 kg object to accelerate it to the right. Determine the acceleration of the object. Show your work.

To determine acceleration, given the force and mass of an object, I would use the Second Law's equation: Force = mass x acceleration. In this equation the force is given as 5.2 N, and the mass is given as 1.05 kg. To solve for acceleration, you would divide the force by the mass. So if you divide 5.2 N by 1.05 kg, you will get 4.95 m/s^2.

Joe has a mass of 100 kg on Earth. What is Joe's mass on the moon where the force of gravity is 1/6th that of the Earth?

100 kg

The amount of net force required to keep a 5 kg object moving with a constant velocity of 2 m/s is...

0 N

According to the Newton's third law, every force is accompanied by an equal and opposite reaction force. The reason that the forces do not cancel each other is...

The two forces act upon different objects

During the contact of a golf club with a golf ball, the force of the club on the ball is _________ the force of the ball on the club and the acceleration of the club is ________ the acceleration of the ball.

equal to; less than

Explain Kinetic Molecular Theory

All matter is composed of tiny particles that are in constant motion.

Explain Boyle’s Law

At a constant temp/amt of gas, pressure and volume will have an inverse relationship. When pressure decreases, volume increases.

Explain Charles’ Law.

At a constant pressure/amt of gas, temperature and volume have a direct relationship. When temperature increases, so will volume.

Explain Gay-Lussac’s Law

At a constant volume/amt of gas, pressure and temperature will have a direct relationship. When temperature increases, so will pressure. 

Is plasma a common state of matter?

NO. It is a hot ionized gas with equal numbers of positively charged ions and negatively charged electrons.

What is sublimination? Provide an example,

The direct change in state from solid to gas. Dry ice.

What is deposition? Provide an example

The direct change in state from gas to solid. Vapor on windows in the winter immediately turning to ice.

Define fluid.

Any liquid or gas that cannot sustain a tangential, or shearing, force when at rest. It undergoes a continuous change in shape when subjected to such stress.

Briefly explain the differences between real and ideal gasses.

• Ideal gasses contain no attractive or repulsive forces between particles, where real gasses have very small attractive/repulsive forces.

• Ideal gasses’ particles have no volume, where real gasses have a very small volume

• Ideal gasses’ collisions are elastic, where real gasses’ collisions are inelastic. 

What is the Ideal Gas Law equation?

PV = nRT

What is the equation for Boyle’s Law?

P1V1 = P2V2

What is the equation for Charles’ Law?

V1T2 = V2T1

What is the equation for Gay-Lussac’s Law?

P1/T1 = P2/T2

What affects the speed of fluid flow?

• magnitude of the force or pressure difference

• volume of the fluid

• viscosity of the fluid

• diameter of the tube which fluid is flowing through

What is the difference between Laminar and Turbulent Flow?

• Laminar flow is when the particles follow a smooth path, paths which never interfere. Velocity is constant

• Turbulent flow is irregular flow, characterized by tiny whirlpool regions. 

All material that takes up space is called

matter

A ________ has a definite volume but no definite shape.

liquid

What type of collision best describes the interactions among particles in an ideal gas?

perfectly elastic

Which of the following does not signal a chemical change?

a change in physical state

An ideal gas is held at a constant temperature while the pressure is increased. What will happen to the volume?

decreases

What is the term describing a change of state from a solid to a gas?

sublimination

An ideal gas is held at a constant pressure while the temperature is decreased. What will happen to the volume?

decrease

An ideal gas is held at a constant volume while the temperature is increased. What will happen to the pressure?

increase

If a gas at 25 degrees C occupies 3.6 liters at a pressure of 1.00 atm.  What will be its volume at a pressure of 2.5 atm? Show your work.

In this problem, you can identify that the pressure and volume are the variables that are changing. Boyle's Law deals with the relationship between pressure and volume, so I will use the Boyle's Law equation: P1 x V1 = P2 x V2. In this problem we are solving for V2 (the second volume), so it can be written as V2= P1 x V1 / P2. We can identify P1 as 1.00 atm, V1 as 3.6 liters, and P2 as 2.5 atm. The temperature can be disregarded because it remains constant. So, to solve for the second volume, you will multiple 1.00 atm by 3.6 liters, and then divide that by 2.5 atm. This will result in a volume of 1.44 liters at a pressure of 2.5 atm. 

600 ml of air is at 20 degrees C.  What is the volume at 60 degrees C?  Please show your work.

In this problem, we are working with the relationship between temperature and volume. Charle's Law deals with the relationship between temperature and volume, and gives us the equation: V1 x T2 = V2 x T1. We are given the initial volume as 600 ml and the initial temperature as 20 degrees C. We are also given the final temperature of 60 degrees C. We will be solving for the final volume, so the equation can be written as V2 = V1 x T2 / T1. Before plugging our values in, we must convert T1 and T2 to Kelvins instead of degrees C. To do so, we will add 273 to each temperature, resulting in T1 being 293 K and T2 being 333 K. Now we can plug our numbers into the equation: V2 = 600 ml x 333 K / 293 K. This will result in a volume of 681.9 ml. 

If a gas is cooled from 323 K to 272 K and the volume is kept constant, what final pressure would result if the original pressure was 750 mm Hg?  Please show your work. 

In this problem, the changing variables are pressure and temperature. Gay Lussac's Law deals with the relationship between pressure and temperature, and gives us the equation: P1/T1 = P2/T2. In this problem we are given both the initial and final temperatures (323 K and 272 K), as well as the initial pressure (750 mm Hg). We will be solving for the final pressure, so the equation can be written as P2 = (P1/T1) x T2. If we plug our given values in, it can be written as: P2 = (750 mm Hg / 323 K) x 272 K. This will result in a final pressure of 631.6 mm Hg.

Differentiate between temperature and heat.

• temperature is the average kinetic energy of the particles in a system

• heat is the transfer of energy from a higher temperature to a lower temp

Explain specific heat capacity.

the amount of heat per unit mass required to raise the temperature of a material by 1 degree Celsius

At what temperatures does water freeze? C, F, K

0 degrees C, 32 degrees F, and 273.15 K

At what temperatures does water boil at? C, F, K

100 degrees C, 212 degrees F, and 373.15 K

Define Energy.

the capacity to do work on a system

What is the first law of thermodynamics?

The change in internal energy of a system is equal to the heat added to the system, minus the work done by the system.

change in internal energy = heat added - work done

What is the second law of thermodynamics?

It places constraints on the direction of heat transfer and the attainable efficiencies of heat engines. Heat flows naturally from hot to cold.

A 1200 Kg car and a 2400 Kg car are lifted to the same height at a constant speed. Lifting the more massive car requires ________work.

twice as much

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ______joules of kinetic energy when she hits the water.

5000

A job is done slowly and an identical job is done quickly. Both jobs require the same amount of ______ but different amounts of ________. 

work; power

Anytime a temperature difference occurs, you can expect...

energy movement from higher temperature regions.

Substance A has a higher specific heat than substance B. With all other factors equal, which requires the most energy to heat equal masses of A and B to the same temperature? 

substance A

A pan made of which substance would require less heat for equal cooking?

copper

According to the laws of thermodynamics...

You cannot convert heat completely into mechanical energy.

What is the basis for the first law of thermodynamics?

conservation of energy

Give two uses for diagnostic ultrasound and two uses for therapeutic ultrasound.

A use for diagnostic ultrasound would be to identify any possible pathologies. This often is used when a patient presents with signs and symptoms suggesting pathology. For example, if a patient presented with right upper quadrant pain, they may get a diagnostic ultrasound and discover anechoic regions on the liver. This could suggest a degenerative liver. Another example would be a patient complaining of urination abnormalities, so they get a diagnostic renal ultrasound and find stones blocking the ureters. Diagnostic ultrasounds are used to identify pathologies, while therapeutic ultrasounds are used to treat pathologies. An example of a therapeutic ultrasound would be using sound waves to crush gallstones. Another example is how ultrasound can be used to treat certain tumors. Therapeutic ultrasound requires the pathology to already be known, or discovered through diagnostic ultrasound, so that it can target the pathology.

Describe two ultrasound-tissue interactions.

One ultrasound-tissue interaction would be attenuation. This is when a sound wave decreases in strength while passing through tissues. Another ultrasound-tissue interaction would be reflection. This is when sound waves are reflected back to the sender after bouncing off a tissue. This can only occur when the two materials have different properties. 

What are the two functions of an ultrasound transducer in terms of energy conversion.

Ultrasound transducers contain crystals that convert electrical energy into acoustic energy. The crystal vibrates, producing the sound wave. When the sound waves are reflected back to the transducer, that acoustic energy is converted back into electrical energy, allowing images to be displayed. 

Define electromagnetic wave

a wave capable of transmitting its energy through a vacuum (microwave, radio, UV, gamma, infrared, visible)

Define mechanical wave

a wave not capable of transmitting its energy through a vacuum. Requires a medium to transport its energy. (water, sound, earthquakes)

Define transverse waves

waves that right angles (perpendicular) to the direction of the wave travel (crests and troughs)

Define longitudinal waves

waves that are parallel to the direction of wave travel (compressions and rarefactions)

Define period

the time which it takes for a particle to complete one full cycle. represented by “T”

Define frequency

the number of complete cycles in a given time, measured in Hertz

What is the equation for frequency?

frequency = 1 / period

What is the equation for wave speed?

velocity = wavelength x frequency

Which of the following statements is true regarding frequency and wavelength of electromagnetic waves?

as frequency increases, wavelength decreases

Compared with light waves, radio waves...

have longer wavelengths

Which property of a wave is defined as the number of pulses or vibrations in a given amount of time.

frequency

What is the wavelength of a 5 Hz wave that travels with a speed of 10 m/s?

2 m

 When the particles of a medium are vibrating at right angles to the direction of energy transport, then the wave is a ______ wave. 

transverse

The main factor which affects the speed of a sound wave is the ________.

properties of the medium

If the frequency of a wave is doubled and if the speed remains constant, its wavelength is __________.

halved

Which phenomenon is produced when two or more waves passing simultaneously through the same medium meet up with one another?

interference

Which one of the following cannot transmit sound?

perfect vacuum

While watching waves pass by a boat docked in the harbor, Joe estimated the crests to be 7.44 m apart.  He used his stopwatch on his phone to determine that a wave crest passed by his position on the deck every 1.6 s.  What was the speed of the ocean waves?  Please show your work.

Using the wave speed equation: velocity = wavelength x frequency, we can solve for the speed of the ocean waves. In this scenario, the wave crests (7.44 m) is the wavelength. The frequency would be the number of waves in the given period of time, 1.6 s. In this equation, Joe timed it to be 1 cycle every 1.6 s. To find the frequency, we would have to use the equation f = 1/ T. The period (T) would be 1.6 s, so 1/1.6s would be 0.625 Hz as the frequency. Now that we have both the frequency (0.625 Hz) and the wavelength (7.44 m), we can plug that into the wave speed equation stated above. This would be (7.44 m) x (0.625 Hz) which equals the velocity 4.65 m/s.

 A sound wave is different than a light wave in that a sound wave is... 

not capable of traveling through a vacuum

 Which of the following best describes the image formed by a plane (flat) mirror?

virtual, upright and the same size as the object

The best definition of refraction is ...

waves changing direction when crossing a boundary

The spreading out of waves as they pass through an opening or around objects is called:

diffraction

Which of the following terms is a useful quantity to describe the loudness of a sound?

intensity

An ultrasound wave has a frequency of 31,000 Hz and a wavelength of .04 m.  In one test, it took .028 ms for the sound to leave the transducer, bounce off the gall bladder and return to the transducer.  Determine how far the gall bladder is from the transducer.  Please show all work.

To determine the distance between the gall bladder and the transducer, we will use the distance equation: d = v x t. The time is given to us as 0.028 ms, which must be converted to seconds by dividing by 1000. This will give us a time of 0.000028 s. For the speed (v), we must use the frequency (31,000 Hz) and the wavelength (0.04 m) given in the equation: v = wavelength x frequency. This would be (31,000 Hz) x (0.04 m) = 1,240 m/s. Now that we have both the time and velocity, we can plug them into the first equation: (1,240 m/s) x (0.000028 s) = 0.03472 m. However, that is the total distance travelled by the wave, not just the returning wave. So, to determine the distance between just the gall bladder and the transducer, we must divide that in half. That would be 0.01736 m between the gall bladder and the transducer. 

What two physical characteristics of a substance affect the speed of sound?

The elasticity and the density of the substance will affect the speed of sound. The elasticity has a direct relationship with sound, as increased elastic objects will produce increased sound. The density of a substance has an inverse relationship with sound, where a more dense substance will decrease sound.

Describe how Color Doppler and Spectral Doppler are used in ultrasonography.

Color Doppler and Spectral Doppler are both used to measure the change in frequency caused by the moving blood in the body. The Doppler effect itself is a change in frequency caused by a moving source, moving receiver, or a moving reflector. The key component being that at least one of the elements are moving. The doppler effect does not work if there is no movement. So, when using the Color Doppler or Spectral Doppler on a stationary object with no blood flow (while remaining stationary yourself), it will not produce any color on the imaging screen. Specifically though, the Color Doppler measures both the speed and direction of blood flow, categorizing blood flowing away from the transducer as blue and towards the transducer as red. The Spectral Doppler bases its measurement off of time and speed. It measures the speed of blood flow through vessels or tissues, and can be used as a diagnostic tool for circulatory disorders.