# Recent content by Lukeblackhill

1. ### Heat during the Day

Hi! My question is: I understand that at noon-day it’s hotter because of the angle with which sun rays enter our atmosphere. But at the same time, I was wondering that the band of radiation responsible for heating things is infrared, and that at noon basically all bands of lower frequency than...
2. ### I Source of Energy in a Field of Forces

Could you explain that in more detail, please? I haven’t found a good material on the matter.
3. ### I Source of Energy in a Field of Forces

good evening! My question is the following: it is well stated that energy is conserved in any isolated system, and we can in most circumstances expand our system to a many-steps conversion of energy, but always conserved. The classic example could be the energy of the sun stored in form of...
4. ### I Changes in Hooke's Law

Morning, I've come across this statement in Berkeley Physics Course, Vol.1 - Cp. 5 (pg.149): "For sufficiently small displacements such a force may be produced by a stretched or compressed spring. For large elastic displacements we must add terms in higher powers of x to Eq. (,5.19): Fx = -...
5. ### B Who drew the first model of the atom?

The first scientist to have a glimpse of the true nature of the atoms was Rutherford. In his experiments (called the Geiger-Mardsen experiments) in 1908, when using golden foils and alpha particles he was able to determine the localization of the positive part of the atom, as the centre of it...
6. ### Question regarding pressure and energy

If you apply a force in a body of volume V, in its area surface A, the body experiences a pressure P=F.A that acts in it in order to peform one or more of this actions, such as a. expanding, b.contracting, c. deforming, d.heating, etc. In all cases, the P.V = W, that is the work done on the...
7. ### Symmetries and Conservation Laws

I've been caught by a quite interesting statement of Berkeley physics Course Vol.1 (Chap. 5), that says "In the physical world there exist a number of conservation laws, some exact and some approximate. A conservation law is usually the consequence of some underlying symmetry in the universe."...
8. ### I Where does the energy go to?

Thank you, @sophiecentaur.
9. ### I Where does the energy go to?

Morning, I was thinking about a simple example of inelastic collision: A ball of mass m1, moving with a certain velocity v1, collides and sticks with another mass m2, at rest. The whole system (m1 + m2) will then move with a certain speed v3. If we take m1=m2, so that after the collision we...
10. ### Reduce Kinetic Energy Losses when Two Objects Collide

I'll try the super-balls, @anorlunda Thank you!
11. ### Measuring Velocity

The idea of the camera is good, @Orodruin. I'll try that. I will also give a look about this Stroboscope. Thank you.
12. ### Reduce Kinetic Energy Losses when Two Objects Collide

I'd like to know which methods I could use to reduce the loss of kinetic energy when two iron balls collide, or when a plastic ball collides with the floor after a free fall. I have tried to cover the floor with a fabric that would make it more elastic, but it had a small effect (if it hat...
13. ### Measuring Velocity

Morning! I was performing some experiments about impulse and conservation of mechanical energy, and for that I was looking to good ways of measuring the velocity of a sphere under the action of a force. In free fall, having the height H it was falling along, I have used the formula v =...