Answer:
One second is defined by taking the fixed numerical value of the caesium frequency ∆ν, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 (9.192631770 x 10⁹ ) cycles of the radiation, when expressed in the unit Hz, which is equal to s−¹.
One second is equal to 1/86,400 of a mean solar day.
Answer:
¢
Explanation:
Given that:
Mass of metal = 12g = 0.012
Density of metal = 4 g/cm³ = 4000kg/m³
Density of oil = 1.5g/cm³ = 1500 kg/m³
Recall : density = mass / volume
Volume of metal, V = mass / density = 0.012/ 4000 = 0.000003
0.000003
T + Density of oil * g * V - (0.012 * 9.8) = 0
T + 1500 * 9.8 * 0.000003 - 0.1176 = 0
T = 0.0441 - 0.1176 = 0
T = 0.1176 - 0.0441
T = 0.0735N
Tension, T
The reflected beam of light passes through the focal point of the mirror.
In fact, a ray travelling parallel to the principal axis of a concave mirror passes through the focal point after it is reflected back from the mirror. This can be seen for instance in this figure:
http://www.cyberphysics.co.uk/graphics/diagrams/light/mirrors/concave_ray1.gif
where the situation described by the problem is shown with the red ray: the beam travels parallel to the principal axis and it is reflected through the focal point.