The arched pipe ha a mass of 80 kg and rest on the surface of the platform for which the coefficient of static friction is equal to 0.3. Determine the greatest angular acceleration of the platform, starting from rest when angle is 45 degrees, without causing the pipe to slip on the platform.

Need more information right now I can tell you it is a weight measurement

How to convert Ounces to Grams How to convert Ounces (oz) to Grams (g).
Ounces to Grams ? Ounces to Grams conversion table Ounces (oz) Grams (g) Kilograms+Grams (kg+g) 0 oz 0 g 0 kg 0 g 0.1 oz 2.835 g 0 kg 2.835 g 1 oz 28.35 g 0 kg 28.35 g 2 oz 56.70 g 0 kg 56.70 g 3 oz 85.05 g 0 kg 85.05 g 4 oz 113.40 g 0 kg 113.40 g 5 oz 141.75 g 0 kg 141.75 g 6 oz 170.10 g 0 kg 170.10 g 7 oz 198.45 g 0 kg 198.45 g 8 oz 226.80 g 0 kg 226.80 g 9 oz 225.15 g 0 kg 225.15 g 10 oz 283.50 g 0 kg 283.50 g 20 oz 566.99 g 0 kg 566.99 g 30 oz 850.49 g 0 kg 850.49 g 40 oz 1133.98 g 1 kg 133.98 g 50 oz 1417.48 g 1 kg 417.48 g 60 oz 1700.97 g 1 kg 700.97 g 70 oz 1984.47 g 1 kg 984.47 g 80 oz 2267.96 g 2 kg 267.96 g 90 oz 2551.46 g 2 kg 551.46 g 100 oz 2834.95 g 2 kg 834.95 g 1000 oz 28349.52 g 28 kg 349.52 g

mass by velocity by the coefficient of the friction
you are missing one dimension of the equation

everything in creation has a coefficient of friction including air
when air is moved over a surface that friction comes into action and the part of the air that is touching the surface is affected by that friction and so is actually slowed down in relation to the air above it
This is air resistance and is subject to certain physical laws regarding air pressures and other laws
The faster the air is made to travel over the surface ,the greater the friction and so the greater the heat being generated ( greater the resistance)
Heat generation is a change of energy from air flow over the surface ( dynamic energy) to heat energy
a reason that objects entering the earth atmosphere , glow red then burn up
the air resistance generates the heat through the friction of the resistance to movement
as an object moves through the air , the air is displaced and as air likes to maintain equal pressure that displacement creates low pressures in the air which have to be filled back to normal
If the air is stopped from from equalizing the pressure ,then a resistance to the movement is registered as the object has a low pressure area around it that slows the movement down or moves the object into that low pressure area
examples are sails on a boat, wings of an aircraft, air flowing over the end of an open pipe
basically air resistance is the resistance caused by the physical properties affected by an object moving through the air.

As given in part three of the question, divide the standard deviation by the average then multiply by 100.

250 kg is sitting on a horizontal surface. Hence, the ground or the horizontal surface is exerting 250 * 9.8 = 2450 N to support the crate. Now, coeff is 750/2450 = 0.306 . The force you have to exert to move crate depends on how heavy the crate is. If crate is heavy you will end up exerting more force. The ratio of the forces provide the coeff of friction.

Sorry, I tried Google translate but there are too many untranslated words : 2 kg dry, 2 kg wet; 3 kg?

This calculator is unable to factor a polynomial expression.
In general there are a few factoring methods

1. Factor by grouping terms
2. Factor by completing the square (quadratic polynomial)
3. Factor by finding two integers such their sum is equal to the coefficient of the middle term, and their product is equal to the third (constant term). This is valid for a quadratic polynomial where the leading coefficient (of the x^2 term) is equal to 1. X^2+SX+P

A cubic equation can be solved algebraically, although two solutions may be complex. Use the Cardano formulas. A quartic equation can be solved by the formulas for the quadratic equation, if you transform the quartic equation to look like A(X^2)^2 + B(X^2) +C=0

I'm not going to do your homework for you, especially since you didn't state the entire problem. I can guess that you need to set up an equation matching the frictional force on the particle at the highest resting point inside the sphere with the force of gravity on the particle (you will need to calculate the angle of the tangent to the sphere in the plane including that point, the bottom of the sphere, and the vertical diameter of the sphere). Will that get you started?

1 kg is equal to 2.2 lb

So, 80 kg = 176lb

Thanks.