A white dwarf can exhibit an astonishing density of ρ ≈ 1000 kg/cm3.  If one had material from a white dwarf that was contained within a paintball of diameter D ≈ 1.8 cm, what would be its mass in kg?   Insert those values directly into the formula: M ≈ ρ x D3 / 2 , and in this instance, provide the answer without units and rounded to the nearest integer (e.g., 80.6 -> 81). 

The extra practice questions don’t count toward a student’s grade. 

Wire 2 is twice the length and has twice the cross-sectional area that of wire 1. What is the ratio R2/R1 of their resistances?

What is the resistance of 1.0 m of a solid cylindrical metal cable having a diameter of 0.40 inches and a resistivity of 1.68 × 10-8 Ω ∙ m?

Compared to the free market, the change in producer surplus from this policy equals

A rational decision maker takes an action only if

Suppose that instead of a tax, government imposes a subsidy of $4. What is the consumer surplus?

Suppose that instead of a price floor, there is a price ceiling equal to $6. Consumer surplus equals

You are the Independent System Operator (ISO) in an electricity market. You have received the bid information in the table below for a double auction. Each buyer’s bid is an offer to buy one unit of electricity. Each seller’s bid is an offer to sell one unit of electricity.

What is the total surplus from this subsidy?