A contact force is a type of force which act on an object by coming in contact with the object. Examples of contact force that acts through a force field are: applied force, frictional force, air resistance force, tension, spring force, etc.
Examples of forces that act through a force field are gravitational force, electromagnetic force, the weak interaction and the strong interaction.
1) Frequency: 
the energy of the photon absorbed must be equal to the ionization enegy of the atom, which is
The energy of a photon is given by
where 
is the Planck's constant. By using the energy written above and by re-arranging thsi formula, we can calculate the frequency of the photon:
2) Wavelength: 91.2 nm
The wavelength of the photon can be found from its frequency, by using the following relationship:
where 
is the speed of light and f is the frequency. Substituting the frequency, we find
Answer:
a charge Q is transferred from an initially uncharged
Explanation:
Hope this helps!
CORRECT ANSWER:
d. Anywhere from days to thousands of years.
STEP-BY-STEP EXPLANATION:
The whole question from book is
How long do molecules of groundwater stay in the
ground?
a. Days
b. Weeks
c. Months
d. Anywhere from days to thousands of years
Answer:
39.6 m/s
Explanation:
Taking down to be positive:
Given:
v₀ = 0 m/s
a = 9.8 m/s²
Δy = 80 m
Find: v
v² = v₀² + 2aΔy
v² = (0 m/s)² + 2 (9.8 m/s²) (80 m)
v = 39.6 m/s
