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What is the equivalence principle of General Relativity and what does it mean?

Einstein introduced the equivalence principle by saying "We ... assume the complete physical equivalence of gravitational field and a corresponding acceleration of the reference system". There are ...
AM
Answered by Andrew M. • Physics tutor
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A piece of card is released from rest at a height of 0.5m above a light gate. It falls freely and a computer measures the velocity as it passes through the light gate to be 3.10m/s. What is the acceleration due to gravity measured by this experiment?

This question can be solved using suvat equations, since the acceleration due to gravity is constant. First make a list of the variables given in the question; s=0.5m u=0ms -1 (since the card is released fro...
HC
Answered by Hannah C. • Physics tutor
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A ball is thrown out of a window 18m off the ground. It is thrown horizontally at 0.5m/s. Show that it takes about 2s to reach the ground

Using the initial information we can see that the acceleration in the 'y' direction is equal to 'g', so from this we can work out the velocity in the 'y' direction 'V(y)' by simply integrating the accelerati...
AJ
Answered by Adam J. • Physics tutor
4672 Views

Why does an absorption spectrum (of eg Helium) show dark lines?

Ignoring the dark lines, we have a continuous colour (visible light) spectrum. The dark lines represent where the photon of a particular wavelength is missing, hence we cant see it. This occurs when the ligh...
JB
Answered by James B. • Physics tutor
9813 Views

What is the De Broglie wavelength of an electron given it has a kinetic energy of 1 eV? You are given the mass of an electron is 9.11x10^-31 kg and Planck's constant is 6.63x10^-34

The De Broglie wavelength equation is as follows: λ=h/p We know the value of Planck's constant h and so to calculate the wavelength all we need is the momentum, which is equal to mv. The kinetic energy is gi...
DM
Answered by David M. • Physics tutor
97938 Views