Explore BrainMass


Mass sliding without friction

A 0.50-kg mass is hooked to two springs as shown in the diagram below. The mass slides without friction, and the spring constant of ONE spring is 15.0 N/m. The mass is given a push, so that its velocity at the equilibrium point (in the middle) is 0.16 m/s. (A) With what frequency does the mass oscillate back and forth? (B)

Speed of an object

An object initially at rest is droped from a height of 20m. What is the speed of the object when it hits the ground? assume g=9.8m/s^2

Drop height to acheive known deflection in a beam

A .5m long beam with 29N-m stiffness is attached to a 45kg weight. The beam is inclined 30 degrees from vertical. Assume the beam has no mass, assume the 45kg weight is "sliding" down a vertical pole of infinite stiffness and zero friction. The mass is dropped and the end of the beam deflects .095m when it contacts the ground.

Physics problem

A potter's wheel -- a thick stone disk of radius 0.500 m and mass 100 kg -- is freely rotating at 50.0 rev/min. The potter can stop the wheel in 6.00 s by pressing a wet rag against the rim and exerting a radially inward force of 65.0 N. Find the effective coefficient of kinetic friction between the wheel and the rag.

Objects sliding down a rough plane...

I have calculated an answer (D), but am not totally sure about its accuracy. Please could you work out the correct answer so I can compare. (See attached file for full problem description)

An electron with a speed 5.00x10^8 cm/s enters an electric field of magnitude 1.00x10^3 N/C, traveling along a field line in the direction that retards its motion. (a) how far will the electron travel in the field before stopping momentarily, and (b) how much time will have elapsed? (c) If the region containing the electric field is .08m long, what fraction of the electron's initial kinetic energy will be lost in that region?

An electron with a speed 5.00x10^8 cm/s enters an electric field of magnitude 1.00x10^3 N/C, traveling along a field line in the direction that retards its motion. (a) how far will the electron travel in the field before stopping momentarily, and (b) how much time will have elapsed? (c) If the region containing the electric fiel

Estimate the change in the Potential Energy.

Estimate, based on the force at the initial and final points, the change in the Potential Energy of a system as the second charge moves to the point (.02475 m,0,0), assuming a stationary charge of -65.07 microC located at the origin, if the second charge of -100.2 microC is initially located at the point (.045 m,0,0).

Energy levels of electron

Determine the lowest four energy levels and wave functions of an electron trapped in an infinitely deep potential well of width 2.0nm. What is the longest wavelength of light emitted by this system?

Planck's constant

If Planck's constant were much, much larger how would this affect our everyday lives?

Calculate how much energy there is in a string

How much energy is there in a string of length 55 meters whose mass density is 7.3g/m, when the string is carrying a traveling wave with amplitude .95 meters and frequecny 77Hz, if the wave velocity is 50 m/s?

Potential and Kinetic energy of an oscillator

A block of mass m = 0.65 kg is fastened to a spring with k = 65 N/m. The block is pulled a distance x = 11 cm from its equilibrium position at x = 0 on a frictionless surface and released from rest at t = 0. v= 1.1 m/s^2 Calculate the potential and kinetic energy of the oscillator when the block is at x = 0.

Solve: Potential Energy

A particle with a charge of 5.5 x 10^-8 C is fixed at the origin. A particle with a charge of -2.3 x 10^-8 is moved from x = 3.5 cm on the x axis to y = 4.3 cm on the y axis. The change in potential energy of the two-particle system is equal to what?

Parallel plates and charge mass

Please show all work and show all equations used and diagrams, etc. etc. so I understand completely please. 1) In separate experiments 4 different particles each start from far away with the same speed and impinge directly on a gold nucleus. the masses and charges of the particles are: 2) Rank the particles according to t

Quantum Mechanics: Time Independent Perturbation

I have a negative potential, -V in the center of an inifinite square well. The well extends from -a to +a and the unperturbed wave functions are: Si sub n (x) = sq root 1/a sin(n*pi*x/2*a) for n even Si sub n (x) = sq root 1/a cos(n*pi*x/2*a) for n odd The perturbation extends from -b to +b and is given by:

Find the kinetic energy

Find the kinetic energy of a cylindrical shaft of mass 2.0 kg and radius 10cm rotating about its central axis at 600 rad/s a. 1800 j b. 1200 j c. 18000 j d. 12000 j

Energy and Momentum: Spring Goes Around Track

The 0.31 kg mass slides on a frictionless wire that lies in the vertical plane. The ideal spring attached to the mass has an equilibrium length of 80 mm and its spring constant is 120 N/m. The mass is released at point A, from rest. Calculate the minimum distance b, if the mass is to slide all the way around the loop to poin

Energy and Momentum: Rebounding Ball

A 0.075 kg ball hits a frictionless, rigid, horizontal surface with a speed of 1.2 m/s at the angle q1 = 70 deg. The angle of rebound is q2 = 62 deg. Compute: a) the speed of the ball immediately after rebound. b) the resultant impulse acting on the ball during its time of contact with the surface. See attachment for

Energy and Momentum: Orbiting Spacecraft

A spacecraft is traveling in a circular orbit (see attached file) around the earth at an altitude of 210 miles. When the craft reaches point A, its engines are fired for a short period, reducing its speed by 7.5%. The resulting path is the (elliptical) crash trajectory AB. Determine the angle b, measured from the nonrotating x

Ball Rolling up an Incline

A 10.0 kg bowling ball of radius 15 cm rolls without slipping along a horizontal surface with a speed of 4.0 m/s as it approaches an incline. What is the total kinetic energy of the ball as it rolls along the horizontal? How high above the floor level will the ball reach (with no slipping) as it rolls up the incline?

One dimension collisions

A ball of mass 1.5kg is thrown upward. it leaves the thrower's hand with a velocity of 10 m/s. Assuming the upward direction is positive: a. how long does it take for the ball to return to the throwers hand b.what is the ball's final velocity just before it reaches the hand? c. what is the change in momentum of the ball?

Propulsive Efficiency

Propulsive efficiency can be defined as the useful power output over the rate of change in energy of the airflow through the engine. If useful power is thrust x velocity, and the rate of change of KE is expressed in terms of air mass flow rate, provide an expression for ηP in these terms. If the efflux pressure is brought

Derive Expression Where Needed

1. A motorcyclist is coasting with the engine off at a steady speed 17 m/s but enters a sandy stretch where the coefficient of friction is .80. Will the cyclist emerge from the sandy stretch without having to start the engine if the sand lasts for 15 m. If so, what will be the speed upon emerging? 2. One car has twice the

Work and Energy

Is Work done = average force * displacement= 1/2 kx^2 = 1/2*31*0.02^2 or 1/2*31*0.02?

Weather Forecasts

Question: It is the middle of winter and the weatherman forecasts a cold, overcast, but dry day, with an average temperatures of -2 degrees Celsius. However, he highlights the presence of a strong wind with a wind chill factor that will make it feel like -10 degrees Celsius. What is meant by the term 'wind chill'? How can it be

Elastic and Inelastic Collisions

A 10 gram bullet is fired horizontally into, and becomes embedded in, a suspended block of wood whose mass is 0.890 kg. (a) How does the speed of the block with the embedded bullet immediately after the collision compare with the initial speed of the bullet? (b) If the block with the embedded bullet swings upward and its center

Yet more simple physics

Think about a rollercoaster. If it loaded at a height of about 500m and then dropped down to almost ground level and was followed by 7 circles where the circles height was about the same it would not work well. Explain in terms of kinetic energy, potential energy, etc. why not. (Picture included if needed.)


An ideal gas mixture consists of 3 kg of Ar and 6 kg of CO2 gases. The mixture is now heated at constant volume from 250 K to 350 K. The amount of heat transfer is: