To reduce friction between two surfaces, you have to
make the surfaces smoother.
The best way to do that is to introduce a fluid between them,
like grease, oil, or air.
Answer:
Thus, the change in the weight of the person is 1.6N , option c is correct.
Explanation:
Uh so I'm no master at this subject, but all stuffs accelerate at 9.8 m/s squared. So you multiply the 9.8 and the 0.20 it's given for reasons unknown other than that's what I see in my notes... and that gives you 1.96 m/s squared.
As for B, I have no idea. I think you may multiply the 1.96 by 4. Tell me your thoughts and maybe we can work it out together
Answer:
Frequency, 
Explanation:
Wavelength of a light wave is 450 nm. It is required to find the frequency of this light wave. The speed of light is given by c. So,

f is the frequency of this light

So, the frequency of this light is
.
Answer:
A
Explanation:
A and B are isotopes of one another but the same element
C and D are isotopes of one another but the same element
However, A and B have a different proton count than C and D, indicating different elements because the proton count is equivalent to the atomic number.