PLLSSSS HELP MARKING BRAINLIST SCIENCE

Physics

1 answer:

Sveta_85 [38]3 years ago

3 0

Answer:

the first one

Explanation: the first one because they were all on two different continents so when they seperated half of the species went on one continent and the other half went onto another one

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If the line spectrum of lithium has a red line at 670.8 nm. How much energy does a a photon with this wavelength have?

Colt1911 [192]

We already know the formula for finding the energy of a photon with this wavelength as:
E = ħc / λ
The information's that we already know are:
h = Plancks constant
= 6.626x10^-34 Js
c = light speed
= 2.999x10^8 m/s
λ = Wavelength of the light as given in the question
 = 670.8x10^-9 m
E = amount of energy
Then
E = (6.626x10^-34) * (2.999x10^8)/ (670.8x10^-9)
= 2.962x10^-19 J

5 0

4 years ago

A pole-vaulter just clears the bar at 5.31 m and falls back to the ground. The change in the vaulter's potential energy during t

irina [24]

Answer:

Weight = 734.46 N

Explanation:

Given:

Initial height of the pole-vaulter is, $h_i=5.31\ m$

Final height of the pole-vaulter is, $h_f=0\ m$

Change in the vaulter's potential energy is, $\Delta U=-3900\ J$

We know that, change in potential energy is given as:

$\Delta U=mg(h_f-h_i)$

Where, 'm' is the mass of the object, 'g' is acceleration due to gravity and has a value of 9.8 m/s².

Now, weight of the object is given as the product of its mass and acceleration due to gravity. So, replace 'mg' by weight 'w'. So, the equation becomes,

$\Delta U = w(h_f-h_i)$