A small block with mass 0.0400 kg slides in a vertical circle of
radius 0.500 m on the inside of a circular track. During one of the
revolutions of the block, when the block is at the bottom of its
path, point A, the magnitude of the normal force exerted
on the block by the track has magnitude 4N . In this same
revolution, when the block reaches the top of its path, point
B, the magnitude of the normal force exerted on the block
has magnitude 0.660 N .
How much work was done on the block by friction during the motion
of the block from point A to point B?
In: Physics
5 kg of saturated water mixture in a rigid container initially at the standard pressure (state 1) is heated at constant volumeto a pressure of 35 MPa (state 2). This heating is performed in such a way that the process passes through the critical point of the water:
a) What is the volume in m3 occupied by the vapor phase and the
liquid phase of the mixture at the initial condition (state
1)?
b) Determine the change in internal energy between the initial
state and final state of the process.
The standard pressure is 101.325 kPa.
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Gaseous calcium atoms absorb light at 423, 272, and 240 nm. After a photon of 272 nm is absorbed from the ground state, a photon of wavelength 672 nm is emitted. After absorption of a photon of 240 nm occurs from the ground state, a photon is emitted of wavelength 504 nm.
1. After the 504 nm photoemission occurs, what wavelength of light (in nm) would have to be emitted for an electron to return to the ground state? Construct an energy diagram to help.
2. What is the energy difference between the second highest and third highest states? Construct an energy diagram to help.
In: Physics
Is your electric blanket safe? It has been theorized that excess
nighttime exposure to electromagnetic fields may reduce the
production of the hormone melatonin in certain women. Furthermore,
reduced melatonin levels might lead to an increased risk of breast
cancer. Scott Davis at Seattle's University of Washington School of
Public Health and Community Medicine was one of the first to
investigate links between electromagnetic fields and cancer
(particularly leukemia). He has been quoted as saying, "Electric
blankets were pretty effectively re-engineered a number of years
ago. Modern-day electric blankets ? anything you buy in the store
now ? (has a different) configuration of the heating elements in
the blanket so that it doesn't produce any magnetic fields." How
could the wiring in an electric blanket be designed to minimize or
eliminate the production of external magnetic fields?
In: Physics
A long, uniform rod of length 0.500 mm and is rotating in a circle on a frictionless table. The axis of rotation is perpendicular to the length of the rod at one end and is stationary. The rod has an angular velocity of 0.42 rad/srad/s and a moment of inertia about the axis of 3.20×10−3 kg⋅m2kg⋅m2 . An insect initially standing on the rod at the axis of rotation decides to walk to the other end of the rod. When the insect has reached the end of the rod and sits there, its tangential speed is 0.173 m/sm/s . The insect can be treated as a point mass.
A) Find the mass of the rod?
B) Find the mass of the insect?
In: Physics
A square plastic chunk with mass 0.750 kg is suspended from the
lower end of a light cord that is 1.66 mm long. The plastic chunk
is stay still in the beginning without any motion. A bullet with
mass 0.0132 kg is on the way to the plastic chunk with a horizontal
velocity v0. The bullet hits the plastic chunk and then embedded in
it. After collision, combined bullet and plastic chunk swings on
the end of the cord. When the plastic chunk has risen a vertical
height of 0.800 mm , the tension in the cord is 4.98 N .
What was the initial velocity v0 of the bullet?
In: Physics
Consider a harmonic electromagnetic plane wave with angular
frequency ω and propagation vector k=(kx,ky,kz) (i.e., propagating
in an arbitrary direction). The electric field vector is
E=(Ex,Ey,Ez) with amplitudes (Exo,Eyo,Ezo) and the magnetic field
vector is B=(Bx,By,Bz) with amplitudes (Bxo,Byo,Bzo).
a) Write an expression for the electric and magnetic waves using
complex representation.
b) Using the laws of electromagnetism without sources (Maxwell’s
equations in free space), prove that k × E = ωB, and k · E =
0
c) What does part b) tell you about the relative directions of k, E
and B?
In: Physics
32.) In the plane of a square conducting frame with the sides a= 8cm, there is an infinite long wire in a distance b= 0.5cm parallel with one side of the square. The infinite wire carries a current with the time functionI(t) = I0·cos(ωt), where I0= 3A,ω= 2pi·f and the frequency is f= 3MHz.
a./ Find the mutual induction coefficient between the wire and the square.
b./ Find the amplitude of the induced voltage.c./ Find the maximal magnetic flux in the square.
In: Physics
A football receiver running straight downfield at 5.50 m/s is
10.0 m in front of the
quarterback when a pass is thrown downfield at 25.0 degree above
the horizon. If the
receiver never changes speed and the ball is caught at the same
height from which it
was thrown:
(a) Draw a diagram of the motion. Include initial and final positions of the runner.
(b) Find the initial speed of the football.
(c) Find the amount of time the football spends in the air
(d) The distance between the quarterback and the receiver when the catch is made.
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a rocket rises vertically from rest, with an acceleration of 3.2 m/s(s) until it runs out of fuel at an altitude of 845 m. After this point, its acceleration is that of gravity, downward. what is the velocity when the rocket runs out of fuel? how long does it take to reach that point? what is the maximum altitude and how long to reach it? what is the velocity when it strikes earth? how long is the rocket in the air?
In: Physics
A uniform magnetic field B is directed into the page.
A circular circuit of radius r containing a
resistor R and a capacitor C, is placed in this field. Initially
the capacitor is uncharged, and at time t =
0, the magnitude of the magnetic field starts to change at a rate
dB/dt = x, x > 0.
a) Using Lenz’s law, determine the direction of the induced current
in the closed loop. Justify
your answer.
b) Calculate the induced emf Ɛ and draw its direction.
c) Write an equation for the circuit as a function of time.
d) Q(t) for this circuit is given as Q(t) = C Ɛ (1−e −t/RC); what
is the voltage VC across the
capacitor as a function of time?
e) What is the power dissipated by the resistor at t = 0 ?
In: Physics
A mass spectrometer is designed to calculate masses of
atoms. A source produces positive ions of
mass m and charge q. The ions move with a velocity v to the right,
pass through a narrow slit S1 and
enter a region between two charged plates. In this region they
experience both an electric and a
magnetic field. The electric field E is caused by the 2 charged
plates; the upper plate is (-) charged
and the lower plate is (+) charged. The magnetic field is B1 and
points out of the page. The ions
exit this region through slit S2 . When they exit, they experience
a new magnetic field B2, that is also
directed out of the page. The ions are then collected inside a
collector.
a) Draw the electric field between the charged plates.
b) With what velocity should ions enter in order to follow a
straight trajectory from S1 to S2?
c) Draw the trajectory followed by the ions in the region of
magnetic field B2? Why does the
trajectory look like this?
d) Where should the collector be placed in the plane containing S2
to collect the ions?
e) What is the mass of the ion in terms of field strengths, charge,
and S2-collector distance?
In: Physics
The initial temperature of the lake at the edge of the mountain glacier is 6.40'C, and the volume of water is 185,000m^3. There is iceberg which the mass is 17.3*10^6kg, temperature is -10'C. The iceberg fell and floated on the lake.
If there is no energy exchange except between the lake and the iceberg, what is the final temperature of the lake and the iceberg?
If there is remaining ice, how much ice is left?
In: Physics
A family on vacation in San Francisco drives from Golden Gate Park due south on 19th Avenue for 2.2 miles and then turns west on Sloat Boulevard and drives an additional 1.1 mile to go to the zoo. The driving time for this trip is 18 minutes. What is the family’s net displacement for this trip? What is the average speed for the trip? What is the average velocity? (Remember to specify the direction of the net displacement and the velocity vectors. This requires giving a reference, like “of the north”, and a direction the angle is measured, like “east” in the direction “20.0° east of north”.)
In: Physics
Kristi Yamaguchi a former figure skater who is the 1992 Olympic Champian, a two-time World Champian and 1992 US Champion. In her 1992 Long Program, she made a sharp turn with a radius of 22.6 m and with a speed of 16.1 m/s. Use Newton's second law to determine the acceleration and the angle of lean of Kristi 55.0-kg body.
Please explain and show work if possible.
In: Physics