Consider the head-on collision between a water molecule, mass 18u and a nitrogen molecule mass 28u. Prior to the collision, the nitrogen moving to the right at +0.4390 km/s and the water molecule is moving to the left at -0.7570 km/s. Immediately after the collision, the velocity of the water molecule is v = 0.6990 km/s. A positive sign indicates a molecule moving to the right and a negative sign indicates a molecule moving to the left. The atomic mass unit (u) is commonly used to indicate the mass of atoms and molecules: 1u=1.66×10^-27kg.

What is the velocity of the nitrogen molecule immediately after the collision? (in m/s)

If the collsion described above is an elastic collision, which of the following MUST conserved?
I. Momentum
II. Kinetic Energy

Explain in words and complete sentences the physical meaning of each of Newton's three laws of motion. Note: Do not simply restate or paraphrase the statements of these laws in your textbook. You must actually explain with suitable examples what the textbook statements mean physically.

A mirror faces a cliff located some distance away. Mounted on the cliff is a second mirror, directly opposite the first mirror a distance 1,772.35 away and facing toward it. A gun is fired very close to the first mirror. The temperature on the day is 26.88 oC. How many times does the muzzle flash of the gun travel the round trip distance between the mirrors before the echo of the the gunshot is heard?

A skateboarder starts up a 1.0-m-high, 30? ramp at a speed of 7.2m/s . The skateboard wheels roll without friction. At the top, she leaves the ramp and sails through the air.

How far from the end of the ramp does the skateboarder touch down?

Diffraction is defined as the bending and spreading of waves around small items, slits, or corners. Sound exhibits diffraction just as light does. In your initial discussion post, address the following:

• Identify two everyday phenomena that exhibit diffraction of sound and explain how diffraction of sound applies.
• Identify two everyday phenomena that exhibit diffraction of light and explain how diffraction of light applies.
• Comparing your examples, what are some significant differences between diffraction of light and diffraction of sound, if any?

identify the pros and cons of using mirrors versus lenses in each of the following applications:

• a large, ground-based, astronomical telescope
• a small “spy” scope
• a terrestrial telescope designed only to read license plates

A physics student who weighs 516.0  N stands on a bathroom scale in an elevator that is supported by an elevator cable; the mass of the elevator, including the student inside, is 868.0  kg . While the student is standing on the scale, the elevator makes an upward trip, followed by a downward trip.

A)Find the magnitude of the acceleration of the elevator at the instant of time when the scale reads 449.0  N

B)What is the tension in the elevator cable in Part (A)?

When the Scale Reads More than the Weight of the Student

At some time during her elevator ride, the scale reads 686.0  N .->>

->> C)What is the magnitude of the acceleration of the elevator if the scale reads 686.0  N ?

D)In which direction is the elevator moving if the scale reads 686.0  N ?

The uncertainty principle arises from a common-sense idea: To measure something, you must affect it somehow. For instance, when you use a pressure gauge to measure air pressure in a car tire you release a small amount of air into the gauge.

• When you shine a light on an object, the momentum from the photons that make up that light impacts the object. For macroscopic objects, this will have no measurable effect. Describe why this is different for atomic-sized objects.
• Suppose you shine a very long wavelength light on one electron and a very short wavelength light on another electron. What differences will you observe?
• Why does shining very short wavelength photons on an electron not tell you exactly where the electron is?
• Describe two other examples of situations in which measuring something about an object somehow changes it.

Land footprint of solar energy:

(a) In 2016, Arizona’s total annual electricity consumption was 78.05 million MWh. What is this in terms of kWh per day?

(b) Land footprint: The average daily insolation in Phoenix is 5.38 kWh/m2/day. Given this daily energy input, how much land area would you need (in square miles) to generate all of Arizona’s daily electricity from the following types of PV panels:

i. Mono-crystalline Si panels with an efficiency of 22 %?

ii. Thin film CdTe with an efficiency of 12%?

(c) Translate to rooftops: Assuming we use 22% efficient mono-crystalline Si panels, how many rooftops would that take if we put the panels on:

i. Wal-Mart stores with an average size of 102,000 square feet?

ii. Household rooftops with an average size of 2,000 square feet?

(d) Reflection: These types of crude statistics get used all the time in public debates about solar energy. Do you think they’re useful? Why or why not? Take about 3-4 sentences to explain what we learn from this exercise and whether you think it’s useful for talking about solar energy.

The figure below is a section of a conducting rod of radius R1=1.30mm and length L=11.00m inside a thick-walled coaxial conducting cylindrical shell of radius R2=10.0R1  and the (same) length L. The net charge on the rod is Q1=-4.30∗10−12C that on the shell is Q2=-4.00Q1.

a) What is the magnitude E of the electric field at a radial distance of r = 2.50R2?

b) What is the direction of the electric field at the radial distance (inward, outward, or zero)? Give reasons!

c) What is the magnitude E of the electric field at a radial distance of r = 3.60R1?

d) What is the direction of the electric field at that radial distance (inward, outward, or zero)? Give reasons

1. What is ductile fracture? What is brittle fracture? (10 pts) 8. Please describe the differences between ductile fracture and brittle fracture. (10 pts)

A stone is dropped from the roof of a building, 1.10s after that a second stone is thrown straight down with an initial speed of 20.0 m/s & the two stones land at the same time

How high is the building h=???m

What is the direction of the magnetic field of a straight, current-carrying wire?

A mass spectrometer is being used to separate common oxygen-16 from the much rarer oxygen-18, taken from a sample of old glacial ice. (The relative abundance of these oxygen isotopes is related to climatic temperature at the time the ice was deposited.) The ratio of the masses of these two ions is 16 to 18, the mass of oxygen-16 is 2.66 × 10-26 kg, and they are both singly charged and travel at 4.9 × 106 m/s in a 1.45 T magnetic field.

What is the separation between their paths in meters when they hit a target after traversing a semicircle?

Δd =