A father (weight W = 849 N) and his daughter (weight W = 394 N) are spending the day at the lake. They are each sitting on a beach ball that is just submerged beneath the water (see the figure). Ignoring the weight of the air in each ball, and the volumes of their legs that are under the water, find (a) the radius of father's ball and (b) the radius of daughter's ball.

A set of crash tests consists of running a test car moving at a speed of 12.6 m/s (27.7 m/h) into a solid wall. Strapped securely in an advanced seat belt system, a 63.0 kg (138.6 lbs) dummy is found to move a distance of 0.720 m from the moment the car touches the wall to the time the car is stopped. Calculate the size of the average force which acts on the dummy during that time.

what is mass?

ive done a course on nuclear physics i could tell you lots of things about quarks and draw feinman diagrams but i feel i should really have learned the answer to the question what is mass.

Most geologists believe that the dinosaurs became extinct 65 million years ago when a large comet or asteroid struck the earth, throwing up so much dust that the sun was blocked out for a period of many months. Suppose an asteroid with a diameter of 2.0 km and a mass of 1.0 ×1013 kg hits the earth (6.0×1024 kg) with an impact speed of 4.2 ×104 m/s.

Part A) What is the earth’s recoil speed after such a collision? (Use a reference frame in which the earth was initially at rest.)

Part B) What percentage is this of the earth’s speed around the sun? The earth orbits the sun at a distance of 1.5×1011 m.

1. In a simple harmonic motion, the kinetic energy is equal to the elastic potential energy in the position:

a) X = A / 2

b) X = A

c) X = A / (2) 1/2

d) X = (2 ) ^1/2 A

e) X = 0

1.2 The displacement of a particle in a simple harmonic motion is given by: X = 10 cos (20t - π / 3), which of the following. expressions is equivalent:

a) X = 10 cos (20t + π / 3)

b) X = 10 sen (20t - 5π / 6)

c) X = 10 sen (20 t + π / 6)

d) X = 10 cos (20 t + 2π / 3)

Thank you!

A chain pulls tangentially on a 47.5 kg uniform cylindrical gear with a tension of 75.1 N. The chain is attached along the outside radius of the gear at 0.864 m from the axis of rotation. Starting from rest, the gear takes 2.62 s to reach its rotational speed of 1.38 rev/s. What is the total frictional torque opposing the rotation of the gear?

(1 point) A rocket is launched from rest and moves in a straight line at 25.0 degrees above the horizontal with an acceleration of 70.0 ?/?^2. After 35.0 s of powered flight, the engines shut off and the rocket follows a parabolic path back to earth.

a)Find the time of flight from launch to impact. HINT: Simple projectile motion after engines are shut down.
HINT: Do not forget to include the engine-on time in your time calculation.

b)What is the maximum altitude reached? HINT: Simple projectile motion after engines are shut down.
HINT: Do not forget to include the height at which the engines are shut down in your calculation.

c)What is the horizontal distance between the launch pad and the impact point? HINT: Simple projectile motion after engines are shut down.
HINT: Do not forget to include the horizontal position at which the engines are shut down in your calculation.

what would the equilibrium temperature of the earth be if it were in mars's orbit? what about venus's orbit?

Show that RC has units of seconds if R is in ? and C is in F

PART A

Which of these affects the energy of an electron that is emitted by a surface exposed to light?SELECT ALL THAT APPLY.

PART B

When photons meet and reflect from a surface and are then detected after they reflect ...

Pick those that are true

PART C

Suppose we have two sources of light, a red one with wavelength 650 nm, and a blue one with wavelength 450 nm. Both produce the same optical power, delivering 1 milliwatt (10^-3 watts) of energy per second per square centimeter to a metal target with an area of 1 cm².

1. Which color would deliver more photons each second?

All the photoelectrons that are produced are collected by another electrode and we determine the current in amperes using a circuit and an "ammeter", that is, some device that can give a precise quantitative measure of the current. Such a device might use the magnetic field generated by the current, or the voltage produced when the current flows across a resistance.

2. If the work function of the surface is 2 eV, will we see a current with both colors, one color, or neither one? If so, how much (in amperes), or if not, explain.

3. If we now increased the power in the light sources by 1000 times, how would that change your answers to part 2?

We want to rotate the direction of polarization of a beam of polarized light through 90° by sending the beam through one or more polarizing sheets. (a) What is the minimum number of sheets required? (b) What is the minimum number of sheets required if the transmitted intensity is to be more than 81% of the original intensity?

QUESTION 1

1. What is the approximate radius of an oxygen nucleus with 8 protons and 8 neutrons?

   	1.	3.02 fm
   	2.	2.4 fm
   	3.	3.53 fm
   	4.	1.10 fm
   	5.	2.89 fm

1 points   

QUESTION 2

1. It is possible to tell α particles from β particles by placing the decaying atom

   in a magnetic field because

   	1.	α particles deflect in the magnetic field but β particles don't
   	2.	β particles deflect in the magnetic field but α particles don't
   	3.	α particles deflect in one direction and β particles in other.
   	4.	α and β particles both deflect in the samedirection but β particles deflect much more.
   	5.	α and β particles both deflect in the same direction but α particles deflect much more.

1 points   

QUESTION 3

1. In terms of the penetrating capabilities of the different types of radiation

   	1.	they all penetrate roughy the same amount of material
   	2.	γ rays can penetrate much deeper than α rays
   	3.	α rays can penetrate much deeper than γ rays
   	4.	β rays can penetrate much deeper than γ rays

1 points   

QUESTION 4

1. Particles which are acted on by the weak nuclear force but not the strong nuclear force are

   referred to as

   	1.	quarks
   	2.	hadrons
   	3.	mesons
   	4.	baryons
   	5.	leptons

1 points   

QUESTION 5

1. When a kilogram of a material has absorbed 0.01 Joules of energy from radiation, we say

   it has received

   	1.	1 rad
   	2.	1 roentgen
   	3.	1 RBE
   	4.	1 curie

1 points   

QUESTION 6

1. Which of the following particles will have a larger biological effect on a human assuming they all

   have the same energy?

   	1.	an X-ray
   	2.	a γ ray
   	3.	a slow neutron
   	4.	an α particle

1 points   

QUESTION 7

1. The purpose of the control rods in a nuclear reactor is to

   	1.	slow down the neutrons given off during fission
   	2.	speed up the neutrons given off during fission
   	3.	absorb the neutrons given off during fission
   	4.	absorb the protons given off during fission
   	5.	absorb the γ rays given off during fission

1 points   

QUESTION 8

1. The purpose of a moderator in a nuclear reactor is to

   	1.	slow down the neutrons given off during fission
   	2.	speed up the neutrons given off during fission
   	3.	absorb the neutrons given off during fission
   	4.	absorb the protons given off during fission
   	5.	absorb the γ rays given off during fission

1 points   

QUESTION 9

1. Which of the four fundamental forces has the largest interaction strength?

   	1.	gravitational force
   	2.	weak nuclear force
   	3.	strong nuclear force
   	4.	electro-magnetic force

1 points   

QUESTION 10

1. It is possible to imagine the human body by looking at the radiation produced from

   the annihilation of matter and antimatter. This is referred to as

   	1.	magnetic resonance imaging (MRI)
   	2.	X-rays
   	3.	computer aided tomography (CAT)
   	4.	positron emission tomography (PET)

1 points   

Apparently there is a gravity anomaly in the Hudson Bay Area in Canada: gravity is "missing" or it is slightly less than it is in the rest of the world.

Does that mean that things in the Hudson Bay Area would theoretically be at a higher gravitational potential, and consequently clocks would run faster there? Would people living there have "more time" than people in other parts of the world - even if over their lives it only amounted to a few nanoseconds?

1. you are given a .5 m^3 container containing 9 moles of an ideal diatomic gas at 0° C, and you want to allow it to reach room temperature (20° C) while staying at the same pressure. You have a choice of holding the volume constant while heating it (process A) and then slowly decompressing the gas isothermally (process B) or simply heating it while maintaining pressure (process C).

a) What is the pressure of the gas?

b) What is the change in internal energy of the gas in going from the initial state to the final state?

c) Calculate the work done and heat transferred during process A. note whether these transfer energy into or out of the gas.

d) Calculate the work done and heat transferred during process B. note whether these transfer energy into or out of the gas.

e) Calculate the work done and heat transferred during process C. note whether these transfer energy into or out of the gas.

f) How do the total work and heat transfer compare for the two methods for getting from the initial state to the final state (AB and C)?

Elements that appear in the same column of the periodic table often share similar chemical properties. In the case of the alkaline earth metals, this is troublesome since the body treats calcium (necessary for proper bone growth) and radium (a radioatictive element) as chemically similar, storing both in bone marrow. The radium then bombards nearby bone cells with alpha particles, causing them to \"crumble.\" Radium poisoning investigations often center on the identification of radium and its isotopes in bone samples using a mass spectrometer. Pictured is a schematic of a simplified mass spectrometer, showing the paths of calcium, barium (another alkaline earth metal) and radium isotopes entering the chamber. The region shown is immersed in a constant magnetic field of 0.352 tesla pointing out of the plane of the schematic. Motion of the positively-charged isotopes toward the right was initiated by a charge separation of 2155 volts on the two plates shown. Using the data shown in the table below, calculate the path radius of the Ca ion. Note that 1 amu = 1.661