(20 points & brainliest!)

Let w denote the weight of the box, n the magnitude of the normal force (the sheet pushing up on the box), k the magnitude of the kinetic friction force, and µ the coefficient of kinetic friction.

The kinetic friction force doesn't kick in until the sheet is tilted at an angle θ₂. Since the box is sliding down at constant speed, it's in equilibrium and the forces acting on it sum to 0.

In the horizontal direction (literally left-and-right, parallel to the ground and not the sheet), we have only the horizontal components of the friction and normal forces to worry about, so that , which reduces to

f cos(θ₂) + n cos(90º + θ₂) = 0

(where we take the right to be positive and left to be negative)

Recall that cos(90º + x) = -sin(x) for all x, and that the friction force is proportional to the normal force by a factor of µ. This gives

µ n cos(θ₂) - n sin(θ₂) = 0

Solve for µ :

µ n cos(θ₂) = n sin(θ₂)

µ = sin(θ₂) / cos(θ₂)

µ = tan(θ₂)

the temperature and the pressure affect solubility. temperature affects by changing the properties of the solvent. the increase in pressure increases solubility, the decrease in pressure decreases solubility.

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.