Hi everyone! The following question is an "assertion and reason type question" from the chapter gravitation:
The answer is both statements are correct and statement 2 is a correct explanation of statement 1.
I wanted to know whether are there any hidden assumptions in this question, like the inclusion of air resistance or local gravity variations in different places on planet earth.
I assume they mean you to ignore air resistance and local variations in gravity. The variation the question mentions would just be the variation with height due to the 1/r^2 law.
Ok sir. Do you remember having a conversation with someone else, regarding projectiles with non-uniform acceleration? If so, could you direct me to that specific transcript, if possible? Google wasn't helpful in this regard. Or maybe even specific keywords would help.
If we were not allowed to neglect the curvature of earth, then I think we can't decompose the velocity components into vertical and horizontal parts as the reference frame itself rotates about the earth's cenrtre.
@GuruVishnu yes, it gets complicated if you cannot neglect the curvature. The trajectory is then an ellipse not a parabola and you have to account for the Earth rotating underneath the particle as it moves.
@GuruVishnu id say that even if you have a small velocity, and even a small height of projection, the acceleration definitely varies. The variation is quite small, but not zero. so the path will be extremely close to a parabolic one, but will not be exactly a parabola
@JohnRennie Ok sir. A small clarification, is the trajectory an ellipse even though the trajectory isn't a complete orbit around earth? If so how can the earth's COM be at one of the foci as per Kepler's first law?
@satan29 Thank you. Sounds reasonable. Maybe that's what we're expected to reason.
@GuruVishnu Outside a sphere the gravitational field is the same as it would be from a point source at the centre of the sphere i.e. Newton's shell theorem. Yes?
Hi! Can anyone explain Davisson–Germer experiment to me? Like how do electrons show diffraction pattern there? I know about wave particle duality but how is the experiment similar (or different?) from the one with light(single slit)?
The Davisson–Germer experiment shone a beam of electrons onto a metal surface.
Each atom on that surface reflected some electrons, so each metal atom on the surface behaved like a point source of electrons.
So in effect the metal surface was behaving like a diffraction grating behaves when you shine light on it, and the reflected electron intensity showed a diffraction pattern.
The wavelength depends on the electron energy. If they included inelastically scattered electrons they'd be receiving electrons with a range of energies and therefore a range of wavelengths
All those different wavelengths would produce overlapping diffracton patterns and the result would be a smeared out mess.
It would be like trying to do a Young's slits experiment with white light instead of a single wavelength.
@Bhavay That doesn't really give you the power to change the question to invalidate the existing answers, however, in this case, sincethe existing answer is not a good one, we can ignore the policy as of now :-)
