Physics Modern Physics Level: High School
Dual Nature
An incident x ray is Compton scattered by a free electron at an angle of 35 degree . A high purity germanium detector is used to detect the scattered x-ray . The detector indicates that the energy of the scattered x ray is 65 keV . What is the energy of the incident x-ray ?
Physics Modern Physics Level: High School
Bohr's Atomic Model
A hydrogen atom is in the fifth excited state when it emits a photon with a wavelength of 1090 nm . Note than n = 2 is the first excited state . Calculate the energy of the atom in the final state .
Physics Electromagnetic Waves Level: High School
The energy density of electromagnetic radiation is some region of space is 10^-12 J/m^3 . Assume that the radiation has wavelength in the middle of the visible range , 550 nm . What is the photon density ?
Physics Electromagnetic Waves Level: High School
Dual Nature
Find the energy of a photon for each of the following cases .
a) a microwave of wavelength 3 cm .
b) blue light of wavelength 420 nm .
c) a radio wave of frequency 1070 kHz .
d) an x-ray of wavelength of 0.1 nm .
Physics Wave Optics Level: High School
An ordinary bright star easily visible to the naked eye emits radiation such that the intensity at the surface of the earth is I = 1.6 x 10^-9 W/m^2 at a wavelength of 560 nm . Estimate the rate at which photons enter the night-adapted eye from such a star . Assume that the pupil diameter is circular , with a diameter of 0.5 cm .
Physics Modern Physics Level: High School
Radioactivity
How much time is required before a 10 mCi sample of 99mTc (t ½ = 6.0 hours) and a 25 mCi sample of 113m In (t ½ = 1.7 hours ) possess equal activities ?
Physics Gravitation Level: High School
Imagine a planet whose mass is about 0.4 times the mass of the earth , while its radius is about 0.4 times the radius of the earth . Estimate the weight on this planet of an object that weighs 399.0 N on earth .
Physics Force & Laws Of Motion Level: High School
Centrifugal Force
A centrifuge is used to separate particles from a solution in which they are suspended . This can only work if they are spun out toward the walls before they come to rest at the bottom of the container. Compare the weight of a particle with force exerted on it by the walls of centrifuge 19.0 cm in diameter rotating at 3200.0 rev / sec . Give your answer as a ratio .
Physics Force & Laws Of Motion Level: High School
Banking
An engineers is to design a highway for the worst case scenario – slick conditions where there is negligible friction between a car’s tires and the road . How steeply should the road be banked at a curve whose radius of curvature is 218.0 m , if it is to be safe for vehicles traveling at 59.0 mph ?
Physics Gravitation Level: High School
Three pennies ( m = 2.5 gm) are placed on an equilateral triangle of side d = 39.0 cm .a) Find the magnitude of the gravitational force exerted by the to penny on the lower right hand penny .
b) Find the magnitude of the net gravitational force on the penny due to the two lower ones.
c) Find the magnitude of the force exerted on a fourth penny placed exactly at the center of the triangle .
Physics Gravitation Level: High School
Imagine a planet whose distance from the sun is approximately 4.9 million miles . The distance of the earth is about 93 million miles . Find the length of this planet’s year in each year and the length of the planet’s year in each years ?
Physics Gravitation Level: High School
An asteroid of mass m1 is initially at rest at a point far from the Earth , where it has negligible gravitational potential energy . The asteroid gradually accelerates under the Earth’s gravitational influence and heads directly towards the Earth . At the same time a satellite is orbiting the Earth in a circular orbit of radius r at a speed given by v0 = sqrt (G ME / r ) Where is G is the gravitational constant and ME is the mass of the Earth . When the asteroid reaches the orbit r it has the speed v1 , what is the relationship between v0 and v1 of the circular orbit ?
Physics Gravitation Level: High School
Calculate the Schwarzchild radius of Cygnus X-1 (block hole) using R = 2 MG / c^2 . Use variables Universal Gravitational Constant (G) ; the mass (M) of the star that collapsed to form the black hole : and the speed of light (c) .
Physics Gravitation Level: High School
A moon rock is thrown upward with initial velocity 7.0 m / s . After 7.0 s it had a downward velocity of 4.0 m / s .a) What is the acceleration due to gravity on the Moon ?
b) How high above the starting point did the rock go before it begins to fall ?
Physics Rotational Mechanics Level: High School
A massless string is wrapped around a solid cylinder . A block of mass m = 2.0 kg hangs from the string . When released , the block falls a distance 82 cm in 2.0 s .a) Calculate the mass of the cylinder .
b) Repeat question using conservation of mechanic energy .
