A“constant” is a parameter that stays the same regardless of the variables. one parameter of the cart that is held constant is the fan speed, acceleration, or mass?

We really don't know for sure, because there's no picture or description
of the cart and you haven't told us anything about it.

But we do know that fan speeds and accelerations are easy to change,
but the mass of things doesn't change.

So I'm pretty sure that it must be the mass of the cart that doesn't change.

Answerthe energy required is 1.60 × 10⁻¹⁸ j, to three significant figures.explanationwe define electric potential as the ratio electric potential energy to the charge,    then the following gives us the potential difference,      the formula  may be on your formula sheet.the change in electric potential energy would be the energy that would needed to move it from point a to point b. solving for that, we get    using q = 8.00  × 10⁻¹⁹ c and  δv = 2.00 v, we get    the energy required is 1.60 × 10⁻¹⁸ j, to three significant figures.

If you're looking for an even spread of clay, silt and sand, add a considerable amount of sand and some clay until the 3 even out". soil texture triangle. silty clay loam soil is approximately 20 percent or less sand, 25 to 40 percent clay, and 40 to 70 percent silt.