How many electrons pass through an ammeter in 16 seconds if the ammeter reading is 2.0 amp? How many electrons go across a diode valve which delivers 16 milliamp for 1 minute?

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ELECTRIC CHARGE

Charge on 1 electron = 1.6 x 10-19 coulomb

1. If a current of 6.0 amp flows for 7.0 seconds, how much charge has moved?

2. If ~a current of 7.2 amp flows for 25 seconds, how much charge has been transferred?

3. What is the current flowing if 96 coulomb pass a point in a circuit in 8.0 seconds?

4. How long will it take a current of 8.0 amp to deliver 104 coulomb?

5. If a battery charger delivers 5 amp into a battery for 2.2 hours, what charge is transferred in the bane*?

6. If a generator can deliver 102 coulomb in 1 min. 40 sec, what current can it generate?

7. How many electrons pass through an ammeter in 16 seconds if the ammeter reading is 2.0 amp?

8. How many electrons go across a diode valve which delivers 16 milliamp for 1 minute?

9. What current is flowing if 6.25 x 1020 electrons pass a point in 5.0 seconds?

10. If 25 million million electrons come out of a battery in 1/100 of a second, what current is flowing?

What were the two most important forces that Milikan worked with in the oil-drop experiment?

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Electric Fields

1) The two objects shown are both positively charged. Which position could possibly have zero electric field?

– A
– B
– C
– D
– They could all have zero electric field

 

2) What were the two most important forces that Milikan worked with in the oil-drop experiment?

– frictional, electrical

– electric, gravitational

– magnetic, gravitational

– electric, magentic

– none are correct

Find the mean lifetime and decay constant for 57Co. If the activity of a 57Co radiation source is now 2.00 mCi, how many 57Co nuclei does the source contain? What will be the activity after one year?

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Physics Question

1. The force constant for the internuclear force in a hydrogen molecule 1H22 is kΚΉ = 576 N/m. A hydrogen atom has mass 1.67 x 10-27 kg. Calculate the zero-point vibrational energy for H2 (that is, the vibrational energy the molecule has in the n = 0 ground vibrational level). How does this energy compare in magnitude with the H2 bond energy of -4.48 eV?

2. The isotope 57Co decays by electron capture to 57Fe with a half- life of 272 days. The 57Fe nucleus is produced in an excited state, and it almost instantaneously emits gamma rays that we can detect.

  • (a) Find the mean lifetime and decay constant for 57Co.
  • (b) If the activity of a 57Co radiation source is now 2.00 mCi, how many 57Co nuclei does the source contain?
  • (c) What will be the activity after one year?

The rod is initially at rest (πœ”π‘– = 0 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐). Let’s take the initial position of the rod to be πœƒ0 = 0 π‘Ÿπ‘Žπ‘‘. How long does it take the rod to rotate to the angle πœƒ = βˆ’πœ‹/2 ?

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Physics M10A, Exam #4, Ch. 9 – Ch. 10

Directions:
There 20 multiple choice questions. Each question is 5 points, and the exam is 100 points. The exam is open book, open notes. However, you may not discuss the exam with your classmates.
Submit your work for each question in Canvas.
𝜏 = π‘ŸπΉ sin πœƒ, 𝜏 = π‘ŸπΉβŠ₯, 𝜏 = π‘ŸβŠ₯𝐹, 𝑔 = 9.8 π‘š/𝑠𝑒𝑐2 ,
πœ” = πœ”π‘– + 𝛼𝑑, πœƒ = πœƒπ‘– + πœ”π‘– 𝑑 + 1
2 𝛼𝑑2, (πœ”)2 = (πœ”π‘– )2 + 2π›ΌΞ”πœƒ, 𝑣 = π‘Ÿπœ”,
π‘Žπ‘‘ = π‘Ÿπ›Ό, 𝜏 = π‘ŸπΉ, πœπ‘›π‘’π‘‘ = 𝐼𝛼, 𝐾𝐸 = 1
2 π‘šπ‘£2 + 1
2 πΌπœ”2, π‘ˆπ‘” = π‘šπ‘”β„Ž, 𝐿 = πΌπœ”

Problems 1–2 refer to the following situation. A beam, resting on two pivots, has a length of 𝐿 = 6.00 π‘š and mass 𝑀 = 90.0 π‘˜π‘”. The pivot under the left end exerts a normal force 𝑁1 on the beam, and the second pivot placed a distance β„“ = 4.00 π‘š from the left end, exerts a normal force 𝑁2. A woman of mass π‘š = 55.0 π‘˜π‘” is a distance π‘₯ = 2.00 π‘š from the left end.
The system is in equilibrium.

 

Problem 1:
What is the normal force 𝑁1?

  • a. 190 N
  • b. 290 N
  • c. 390 N
  • d. 490 N

Problem 2:

What is the normal force 𝑁2?

  • a. 831 N
  • b. 931 N
  • c. 1031 N
  • d. 1131 N
Problems 3–4 refer to the following situation. The chewing muscle, the masseter, is one of the strongest in the human body. It is attached to the mandible (lower jawbone) as shown in the Figure below on the left. The jawbone is pivoted about a socket just in front of the auditory canal. The forces acting on the jawbone are equivalent to those acting on the curved bar in Figure below on the right. 𝐹𝐢 is the force exerted by the food being chewed against the jawbone, 𝑇 is the force of tension in the masseter, and 𝑅 is the force exerted by the socket on the mandible. We will consider 𝐹𝐢 = 50.0 𝑁. The system is in equilibrium.

Problem 3:
What is 𝑇, the force of tension in the masseter?

  • a. 57.1 N
  • b. 107.1 N
  • c. 157.1 N
  • d. 207.1 N

Problem 4:
What is 𝑅, the force exerted by the socket on the mandible?

  • a. 57.1 N
  • b. 107.1 N
  • c. 157.1 N
  • d. 207.1 N
Problems 5–7 refer to the following situation. A person bending forward to lift a load β€œwith his back” (see figure below on the left) rather than β€œwith his knees” can be injured by large forces exerted on the muscles and vertebrae. The spine pivots mainly at the fifth lumbar vertebra, with the principal supporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved, and to understand why back problems are common among humans, consider the model shown in the figure below on the right of a person bending forward to lift a 200 N object. The spine and upper body are represented as a uniform horizontal rod of length 45.0 cm and weight 350 N, pivoted at the base of the spine. The erector spinalis muscle, attached at a point two thirds of the way up the spine (a distance of 30.0 cm from the spine), maintains the position of the back. The angle between the spine and this muscle is 12.0∘. The system is in equilibrium.

Problem 5:
What is the tension 𝑇?

  • a. 2705.5 N
  • b. 2905.5 N
  • c. 3105.5 N
  • d. 3305.5 N

Problem 6:
What is the x–component of the force on the spine, 𝑅π‘₯?

  • a. 2146.4 N
  • b. 2646.4 N
  • c. 3146.4 N
  • d. 3646.1 N

Problem 7:
What is the y–component of the force on the spine, 𝑅𝑦?

  • a. βˆ’42.5 𝑁
  • b. βˆ’32.5 𝑁
  • c. βˆ’22.5 𝑁
  • d. βˆ’12.5 𝑁
Problems 8–13 refer to the following situation. Two forces 𝐹1 and 𝐹2 are acting on a rod, as shown in the figure below. The rod is pivoted about point 𝑂, on the left end of the rod.

Problem 8:
What is the torque due to 𝐹1, about point 𝑂?

  • a. βˆ’10.0 𝑁 β‹… π‘š
  • b. βˆ’20.0 𝑁 β‹… π‘š
  • c. βˆ’30.0 𝑁 β‹… π‘š
  • d. βˆ’40.0 𝑁 β‹… π‘š

Problem 9:
What is the torque due to 𝐹2, about point 𝑂?

  • a. 12.0 𝑁 β‹… π‘š
  • b. 22.0 𝑁 β‹… π‘š
  • c. 32.0 𝑁 β‹… π‘š
  • d. 42.0 𝑁 β‹… π‘š

Problem 10:
What is the net torque about point 𝑂?

  • a. βˆ’18.0 𝑁 β‹… π‘š
  • b. βˆ’28.0 𝑁 β‹… π‘š
  • c. βˆ’38.0 𝑁 β‹… π‘š
  • d. βˆ’48.0 𝑁 β‹… π‘š

Problem 11:
What is the moment of inertia of the rod about the point 𝑂? The formula for the moment of inertia of a rod, about one of its ends, is 𝐼 = π‘šπΏ2/3, where π‘š is the mass of the rod and 𝐿 is the length of the rod. The rod has a mass of 1.5 π‘˜π‘” and a length of 5.00 m.

  • a. 8.5 π‘˜π‘” β‹… π‘š2
  • b. 10.5 π‘˜π‘” β‹… π‘š2
  • c. 12.5 π‘˜π‘” β‹… π‘š2
  • d. 14.5 π‘˜π‘” β‹… π‘š2

Problem 12:
What is the angular acceleration of the rod?

  • a. βˆ’1.24 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • b. βˆ’2.24 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • c. βˆ’3.24 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • d. βˆ’4.24 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2

Problem 13:
The rod is initially at rest (πœ”π‘– = 0 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐). Let’s take the initial position of the rod to be πœƒ0 = 0 π‘Ÿπ‘Žπ‘‘. How long does it take the rod to rotate to the angle πœƒ = βˆ’πœ‹/2 ?

  • a. 0.88 sec
  • b. 1.18 sec
  • c. 1.48 sec
  • d. 1.78 sec
Problems 14–17 refer to the following situation. A uniform solid disk with mass 40.0 kg and radius 0.200 m is pivoted at its center about a horizontal, frictionless axle that is stationary. The disk is initially at rest, and then a constant force 𝐹 = 30.0 𝑁 is applied tangent to the rim of the disk. The moment of inertia of a solid disk is 𝐼 = 𝑀𝑅2/2, where 𝑀 is the mass of the disk and 𝑅 is the radius of the disk.

Problem 14:
What is the net torque acting on the disk?

  • a. 2.00 𝑁 β‹… π‘š
  • b. 4.00 𝑁 β‹… π‘š
  • c. 6.00 𝑁 β‹… π‘š
  • d. 8.00 𝑁 β‹… π‘š

Problem 15:
What is the angular acceleration of the disk?

  • a. 6.50 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • b. 7.50 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • c. 8.50 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2
  • d. 9.50 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐2

Problem 16:
What is the angular speed of the disk after 0.400 sec?

  • a. 1.00 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐
  • b. 2.00 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐
  • c. 3.00 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐
  • d. 4.00 π‘Ÿπ‘Žπ‘‘/𝑠𝑒𝑐

Problem 17:
Let’s define the initial angular position of the disk as πœƒ0 = 0 π‘Ÿπ‘Žπ‘‘. What is the angular position of the disk, πœƒ, after 0.400 sec?

  • a. 0.200 rad
  • b. 0.400 rad
  • c. 0.600 rad
  • d. 0.800 rad

Problems 18–20 refer to the following situation. A solid, horizontal cylinder of mass 10.0 kg and radius 1.00 m rotates with an angular speed of 7.00 rad/sec about a fixed vertical axis through its center. A 0.250 kg piece of putty is dropped vertically onto the cylinder at a point 0.900 m from the center of rotation and sticks to the cylinder. The moment of inertia of a solid disk is 𝐼 = 𝑀𝑅2/2, where 𝑀 is the mass of the disk and 𝑅 is the radius of the disk. Treat the piece of putty as particle. The moment of inertia of a particle is 𝐼 = π‘šπ‘Ÿ2, where π‘š is the mass of the particle and π‘Ÿ is the distance of the particle from the axis of rotation.

Problem 18:
What is the moment of inertia of the disk?

  • a. 5.00 π‘˜π‘” β‹… π‘š2
  • b. 6.00 π‘˜π‘” β‹… π‘š2
  • c. 7.00 π‘˜π‘” β‹… π‘š2
  • d. 8.00 π‘˜π‘” β‹… π‘š2

Problem 19:
What is the moment of inertia of the disk and the piece of putty?

  • a. 5.20 π‘˜π‘” β‹… π‘š2
  • b. 6.20 π‘˜π‘” β‹… π‘š2
  • c. 7.20 π‘˜π‘” β‹… π‘š2
  • d. 8.20 π‘˜π‘” β‹… π‘š2

Problem 20:
What is the angular speed of the system after the piece of putty is dropped on the disk?Β Β  Hint: Use conservation of angular momentum.

  • a. 5.73 rad/sec
  • b. 6.73 rad/sec
  • c. 7.73 rad/sec
  • d. 8.83 rad/sec

The force per meter between the two wires of a jumper cable being used to start a stalled car is 0.225 N/m. (a) What is the current in the wires, given they are separated by 2.00 cm? (b) Is the force attractive or repulsive?

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Physics Homework#1, T,3

Answer the following questions (show your full work)

  1. Use the diagram given to find the force per unit length between the two wires shown.

 

  1. The distance between two parallel wires carrying currents of 10Β A and 20Β A is 10Β cm. Determine the magnitude and direction of the magnetic force acting on the length of 1Β m of wires, if the currents are carried a) in the same direction, b) in the opposite direction.

 

  1. The force per meter between the two wires of a jumper cable being used to start a stalled car is 0.225 N/m. (a) What is the current in the wires, given they are separated by 2.00 cm? (b) Is the force attractive or repulsive?

 

  1. The wire carrying 400 A to the motor of a commuter train feels an attractive force of 4.00 Γ— 10βˆ’3 N/m due to a parallel wire carrying 5.00 A to a headlight. (a) How far apart are the wires? (b) Are the currents in the same direction?

 

  1. A 2.50-m segment of wire supplying current to the motor of a submerged submarine carries 1000 A and feels a 4.00-N repulsive force from a parallel wire 5.00 cm away. What is the direction and magnitude of the current in the other wire?

Comment on the widespread use of wave and tidal power as a source of renewable energy. Does it seem reasonable? Can it be a significant part of our future energy budget?

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Extra Credit Assignment

This extra credit assignment is worth up to 10% of your final grade and can only be used to help your final game.

Consider and address any one (1) of the three (3) issues below. You may only choose one. You must argue in favor of a specific position. For example, if the issue were to consider the possibility of solar panels to generate a sufficiently large amount of electricity to reduce significantly our reliance on fossil fuels within two decades, then you could argue any of several positions. You could argue that it is not feasible to do so, you could argue that it is, or you could argue some intermediate position. You must con-struct a written argument that fills fewer than three (3) written pages in 12pt font. Your position must be stated clearly and unambiguously. Your argument must be based primarily upon evidence and theory and as little as possible upon anecdotes or opinions. Your argument must cite at least two reputable sources. In general, the vast majority of blog posts, you tube videos, and even a large number of newspapers are not reputable sources. You may ask me to suggest reputable sources if you are having trouble.

The Issues:
(1) Comment on the amount of energy used in two scenarios. In the first scenario, most Americans obtain most of their consumer goods and groceries from brick-and-mortar shops. In the second scenario, most Americans obtain their consumer goods and groceries from large on-line retailers such as Amazon.
(2) Comment on the widespread use of wave and tidal power as a source of renewable energy. Does it seem reasonable? Can it be a significant part of our future energy budget?
(3) Comment on expanding nuclear power as a source of energy that produces little greenhouse gas emissions. Is it reasonable? What are the risks and rewards?

Write a 2000-word limit paper about “Thermonuclear weapons are 1000 times stronger than any other.” stick to the criteria paper.

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Physics IA3 assignment: Research Investigation

Write a 2000-word limit paper about “Thermonuclear weapons are 1000 times stronger than any other.” stick to the criteria paper. The Task is: Gather secondary evidence related to a research question in order to evaluate the claim. Develop your research question based on a number of possible claims provided by your teacher. Evidence must be obtained by researching scientifically credible sources, such as scientific journals, books by well-credentialed scientists, and websites of governments, universities, independent research bodies, or science and technology manufacturers.

Research conventions must be adhered to. Criteria: For the Research and Planning:

  • Β informed application of understanding of heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by a considered rationale identifying clear development of the research question from the claim
  • Β effective and efficient investigation of heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by – a specific and relevant research question – selection of sufficient and relevant sources.

For Analysis and interpretation: β€’ systematic and effective analysis of qualitative data and/or quantitative data within the sources about heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by – the identification of sufficient and relevant evidence – thorough identification of relevant trends, patterns or relationships – thorough and appropriate identification of limitations of evidence β€’ insightful interpretation of research evidence about heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by justified scientific argument/s. For Conclusion and evaluation: β€’ insightful interpretation of research evidence about heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by justified conclusion/s linked to the research question β€’ critical evaluation of the research processes, claims and conclusions heating processes, ionising radiation & nuclear reactions, electrical circuits, or linear motion and force demonstrated by – insightful discussion of the quality of evidence – extrapolation of credible findings of the research to the claim – suggested improvements and extensions to the investigation which are considered and relevant to the claim. For communication: β€’ effective communication of understandings and research findings, arguments and conclusions about heating processes, ionising radiation & nuclear reactions, electrical circuits, linear motion and force demonstrated by – fluent and concise use of scientific language and representations – appropriate use of genre conventions – acknowledgment of sources of information through appropriate use of referencing conventions.

Using your value for the most probable speed at 298 K for oxygen determined in part 3, determine the fraction of molecules at 298 K and at 500 K which have speeds greater than this speed.

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The Kinetic Theory of Gases

A Maple Exercise
The kinetic theory of gases is one of the cornerstones of physical chemistry. It provides a model that allows the calculation of many dynamic properties of a perfect gas. Knowledge of molecular speeds and their distribution functions is useful in understanding the rates of gas phase reactions.

Theory
The kinetic theory of gases was developed from a model that incorporated the following features:
a) the gas consists of large numbers of particles in continual random motion,
b) the size of the particles is negligible in comparison to the average distance traveled between collisions, and
c) the particles exert no intermolecular forces on one another and thus their collisions are perfectly elastic.

The predictions of the kinetic theory are found to agree well with the actual behavior of real gases at normal pressures and temperatures well above their boiling points.
According to the kinetic theory, the temperature of a gas is a measure of the average translational kinetic energy of the gas, and is thus also a measure of the average speed, <c>, of the gas particles. Common sense (and experimental results) tells us that not all gas particles move with the average speed — some move faster than average and some slower. A distribution function provides the fraction of molecules with speeds between c and c + dc. The distribution function for perfect gases is called the Maxwell-Boltzmann distribution function and is given below:
F(c) dc = 4
Ο€ m
2
Ο€kT

ο£­
 
ο£Έ
ο£·
3/2
c2 exp βˆ’ mc2
2kT

ο£­

ο£Ά
ο£Έ
ο£·ο£· dc [1]
where m is the molecular mass, k is the Boltzmann constant, and T is the Kelvin temperature. Note especially the dependence of this function on mass and temperature. This equation can be plotted as a function of c to see how the fraction of molecules with a given speed changes with speed or temperature. The above equation can also be used for several purposes. The maximum of the distribution function provides the most probable speed, c *. Differentiating Equation [1] with respect to c and solving for c when the derivative equals zero one obtains the most probable speed. c* = 2kT
m

ο£­
 
ο£Έ
ο£·
1/ 2

The fraction of particles with speeds between c 1 and c 2 can be obtained by integrating equation [1] between c 1 and c 2.
One of the most powerful uses of distribution functions is calculating averages. For any distribution function F(x), the average of any property which depends on x (such as ΞΎ) is given byΞΎ = ΞΎ F(x)∫ dx [3] Using this, the average speed can be determined by evaluating c = c F(c)∫ dc [4] where the limits of integration range from c=0 to c=∞. The resulting integral is c = 8kTΟ€m

ο£­
 
ο£Έ
ο£·
1/2

In a similar manner, the root-mean-square speed, c rms, is determined by evaluating c2 1/ 2 ≑ crms = c2 F(c)dc∫( )1/ 2
The integral evaluates to the following simple expression. crms = 3kT
m

ο£­
 
ο£Έ
ο£·
1/ 2

The root-mean-square speed is particularly useful since the average translational kinetic energy EK is given by
EK = 1
2 m c2 = 1
2 mcrms
2
Combining equations [7] and [8] yields
EK = 3
2 kT

the average translational energy per particle for a perfect gas. This result agrees well with experimental values for monatomic gases. Note that the average kinetic energy is not a function of the mass of the particles involved.
The kinetic theory also provides information regarding molecular collisions. The number of collisions experienced by a single particle per second per unit volume is given by
z A = 2
Ο€d2 c N
V = 2
Ο€d2 c p
kT

where d is the molecular diameter and N the number of particles per volume V. The quantity Ο€ d2 is often called the collision cross section and is given the symbol
Οƒ. The total number of collisions between particles per second per unit volume is given by Z AA = Ο€d2 c N2 2

Calculations
1. Determine the Maxwell-Boltzmann distribution function for hydrogen gas and oxygen gas at 298 K (plot data for both on same graph). Remember, these gases are diatomic and check you units!

2. Determine the Maxwell-Boltzmann distribution function for oxygen at 298 K and 500 K (plot data for both on same graph)

3. Determine the most probable speed for oxygen at 298 K and 500 K.

4. Using your value for the most probable speed at 298 K for oxygen determined in part 3, determine the fraction of molecules at 298 K and at 500 K which have speeds greater than this speed. Assuming this is the minimum speed required for molecules to be travelling in order to react in some specific reaction, estimate the relative reaction rates at the two temperatures. Make sure you use the same speed for both curves.

Watch an episode of NOVA and Write about 5 things you learned, 3 things you wondered about, and how do you learn more about them.

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Summary of a Nova episode

Watch an episode of NOVA and Write about 5 things you learned, 3 things you wondered about, and how do you learn more about them.

How far from the base of the ramp should the rocket start, as measured along the surface of the ramp?

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Two physics home work problems

Screenshot 2023-04-07 4.30.45 PM.png

A ballistic pendulum is used to measure the speed of a fast-moving objects such as bullets. If a bullet is fired into a large block suspended by some light wires.

The bullet is stopped by the block, and the entire system swings up to a height h.

If the mass of the bullet is m=27g, the mass of the pendulum is M=0.61kg, and the height they rise to after the bullet strikes the mass is h=20cm.

Calculate the initial speed of the bullet, v (in m/s).

 

Screenshot 2023-04-07 4.32.06 PM.png

A 100kg rocket is to be launched with an initial upward speed of 50m/s.

In order to assist its engines, the engineers will start it from rest on a ramp that rises 59Β° above the horizontal.

At the bottom, the ramp turns upward and launches the rocket vertically.

The engines provide a constant forward thrust of 2,435N, and friction with the ramp surface is a constant 567N.

How far from the base of the ramp should the rocket start, as measured along the surface of the ramp?