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Answer:
We conclude that the mass of a rock with a force of 500 N and an acceleration of 75 m/s² is 6.7 kg.
Hence, option D is correct.
Explanation:
Given
To determine
Mass m = ?
Important Tip:
-
The mass of a rock can be found using the formula F = ma
Using the formula

where
- a is the acceleration (m/s²)
now substituting F = 500, and a = 75 m/s² in the formula


switch sides

Divide both sides by 75

simplify

kg
Therefore, we conclude that the mass of a rock with a force of 500 N and an acceleration of 75 m/s² is 6.7 kg.
Hence, option D is correct.
#39. rain, snow, sleet and hail.
1 nanowatt = 1 nanojoule/sec
1 watt = 1 joule/sec
10 watts = 10 joules/sec
100 watts = 100 joules/sec
742.914 watts = 742.914 joules/sec
1,000 watts = 1,000 joules/sec
10,000 watts = 10,000 joules/sec
100,000 watts = 100,000 joules/sec
1 megawatt = 1 megajoule/sec
1 gigawatt = 1 gigajoule/sec
1 petawatt = 1 petajoule/sec
We don't care what frequency the transmission is using,
or who their morning DJ is.
A) We want to find the work function of the potassium. Apply this equation:
E = 1243/λ - Φ
E = energy of photoelectron, λ = incoming light wavelength, Φ = potassium work function
Given values:
E = 2.93eV, λ = 240nm
Plug in and solve for Φ:
2.93 = 1243/240 - Φ
Φ = 2.25eV
B) We want to find the threshold wavelength, i.e. find the wavelength such that the energy E of the photoelectrons is 0eV. Plug in E = 0eV and Φ = 2.25eV and solve for the threshold wavelength λ:
E = 1243/λ - Φ
0 = 1243/λ - Φ
0 = 1243/λ - 2.25
λ = 552nm
C) We want to find the frequency associated with the threshold wavelength. Apply this equation:
c = fλ
c = speed of light in a vacuum, f = frequency, λ = wavelength
Given values:
c = 3×10⁸m/s, λ = 5.52×10⁻⁷m
Plug in and solve for f:
3×10⁸ = f(5.52×10⁻⁷)
f = 5.43×10¹⁴Hz