P. 4084. An axe is wedged in a piece of wood. In which case will the wood be split more easily: if the support is hit
X) by the poll (butt) of the axe, or
Y) by the piece of wood?
a) It does not matter by which of the above the support is hit.
b) The support is to be hit by that one which has the smaller mass.
c) The support is to be hit by the piece of wood, because in this case the piece of wood stops, and the axe will penetrate into the wood even more deeply, due to its inertia.
d) In case Y because the axe is made of iron thus its mass is greater.
P. 4092. A laser emits light impulses of wavelength 580 nm and of energy 20 J, which last for 0.5 ms. This light is aimed perpendicularly at a sheet made of caesium, and is focused to a circle of diameter 12 mm. 90% of the light is absorbed and 10% is reflected.
a) How many photons hit the metal sheet during one impulse?
b) Find the pressure of light.
c) Find the maximum of the speed of the electrons which are ejected by the caesium sheet.