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A ball of mass 500g is dropped from rest 2m above the ground. When it reaches the ground it is travelling at 5m/s. How much energy has been dissipated?

Initial energy (Gravitational Potential): E = mgh = 0.5 x 9.81 x 2 = 9.81J Final energy (Kinetic): E = mv²/2 = (0.5 x 5²)/2 = 6.25J Energy lost = 9.81 - 6.25 = 3.56J

Answered by Georgina B. • Physics tutor

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Explain why excited atoms only emit certain frequencies of radiation after an electron collides with the atom

Radiation is emitted via photons2) Photon energy is governed by the equation E = hc/wavelength, where h = the Planck constant and c = the speed of light. Both h and c are constants3) Electrons have ...

Answered by Michael H. • Physics tutor

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I do 400J of work compressing a gas, but I maintain the same temperature. What is the delta U, Q and W in this case?

U = 0Q = -400W = -400

Answered by Helen C. • Physics tutor

2158 Views

A trolley of mass 0.75kg is running along a frictionless track at a constant speed of 0.7ms-1, as the trolley passes below a mass of 0.5kg the mass drops a short vertical distance onto the trolley. Calculate the new velocity of the trolley and mass.

Momentum = mass x velocityInitial momentum = 0.75 x 0.7 =0.525kgms-1Momentum is assumed conserved so final momentum = 0.525kgms-1So final mass = 0.5+0.75 = 1.25kgSo final velocity = 0.525/1.25Final veloci...

Answered by Alexander M. • Physics tutor

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