The state of matter that has particles that slide by one another is liquid because liquid is very slippery.
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50N is your force and the acceleration is -9.8m/s^2 due to gravity.
So, you just plug that in.

BUT you know that mass cannot be negative, so you just disregard the negative sign and the mass of the rock is 5.102 grams.
I think that from the answers above the answer is B.
Complete Question
At what angle should the axes of two Polaroids be placed so as to reduce the intensity of the incident unpolarized light to 1/5.
Answer:
The angle is
Explanation:
From the question we are told that
The light emerging from second Polaroid is 1/5 the unpolarized
Generally the intensity of light emerging from the first Polaroid is mathematically represented as

Generally from the Malus law the intensity of light emerging from the second Polaroid is mathematically represented

=> 
=> 
From the question


=> ![\theta = cos ^{-1} [\sqrt{\frac{2}{5}} ]](https://tex.z-dn.net/?f=%5Ctheta%20%3D%20%20%20cos%20%5E%7B-1%7D%20%5B%5Csqrt%7B%5Cfrac%7B2%7D%7B5%7D%7D%20%20%5D)
=> 
Is is the second one. 336 k. 273.15K= 0C.