Answer:
2.9 E14 Hz
Explanation:
As we know by Einstein's equation that energy incident on the photo sensitive surface will be used by the surface to eject electron out of the surface with some kinetic energy.
This is given by

now the threshold frequency is the minimum frequency of the incident photons due to which electrons are ejected out with minimum kinetic energy or least kinetic energy.
So here when KE = 0 in the graph then corresponding to that position the frequency will be given as threshold frequency
so here from graph when KE = 0

Answer:
Distance is 50m
Displacement is 0m
Explanation:
Distance is based on the amount of length you covered, regardless of where you end.
Displacement only considered where you started and where you ended, which is at the same spot in this case. Therefore, no displacement.
Answer:
3.982 kg
Explanation:
The latent heat of vaporization = 540 cal/g
= 5.4 ×10⁵ cal/kg
L = 5.4 ×10⁵ × 4.19
= 2.26 × 10⁶ J/kg
Q = 12 × 750,000
= 9, 000, 000
= 9 × 10⁶ J
the maximum number of kg of water (at 100 degrees Celsius) that could be boiled into steam (at 100 degrees Celsius) is:
= 
= 3.982 kg
Johannes Kepler was a main stargazer of the Scientific Revolution known for detailing the Laws of Planetary Motion. A stargazer, obviously, is a man who contemplates the sun, stars, planets and different parts of room. Kepler was German and lived in the vicinity of 1571 and 1630.
Despite the fact that Kepler is best known for characterizing laws in regards to planetary movement, he made a few other striking commitments to science. He was the first to discover that refraction drives vision in the eye and that utilizing two eyes empowers profundity recognition.