Prices of related goods
When cinema admission rises, demand for community-theatre tickets increases as audiences switch entertainment options.
Chapter 3 · Interactive course companion
Equilibrium,
in motion.
Play a demand shift. Play a supply shift. Then change or drag either curve and solve the new equilibrium price and quantity.
- 3focused labs
fixed axes reveal the movement
PlayAnimate a curve from its original position.
PauseStop at any point and inspect the imbalance.
SolveDrag or parameterize curves and verify the new equilibrium.
01
Buyers change their plans
Play a demand shift
Use the market for weekend paddleboard rentals. Select a rightward increase or leftward decrease, then play the transition. Supply and both axes remain fixed, so the imbalance and movement to the new equilibrium stay visually comparable.
Demand changes; supply does not
Watch the market move from E₀ to the new equilibrium
What shifts demand?
Demand shift factors · six separate scenarios
Expected future prices
A formalwear shop announces higher rental rates next month, increasing current bookings before the change.
Income
Higher freelance earnings increase demand for delivered meal kits, treated here as a normal good.
Expected income and credit
Confirmed harvest payments make farm operators more willing to book equipment repairs today.
Number of buyers
A relocated government office adds workers to a district, increasing demand for neighborhood laundry services.
Preferences
A public astronomy festival increases demand for telescope rentals.
02
Sellers change their plans
Play a supply shift
Use the same weekend paddleboard-rental market. Select a rightward increase or leftward decrease, then play the transition. Demand and the axes remain fixed, revealing the price movement along the unchanged demand curve.
Supply changes; demand does not
Watch the market move from E₀ to the new equilibrium
What shifts supply?
Supply shift factors · six separate scenarios
Prices of productive resources
Cheaper biodegradable resin increases the supply of reusable food containers.
Prices of related outputs
A higher price for wool blankets leads textile workshops to supply fewer fleece throws.
Expected future prices
Flower growers expecting lower prices next week offer more cut flowers for sale today.
Number of sellers
New mobile groomers entering a district increase the supply of pet-grooming appointments.
Technology
Optical sorting cameras let recycling centers process more glass per shift, increasing supply.
Natural conditions
Stronger seasonal winds increase the supply of wind-farm electricity.
03
The market solves two plans at once
Drag, parameterize, and solve equilibrium
Change either intercept or slope. You can also drag a curve directly to shift its intercept while preserving its slope. The graph, algebra, equilibrium price, and equilibrium quantity update together on fixed axes.
Solve Qd = Qs
Every curve change creates a new market solution
Chapter 3 · Demand and supply
A shift changes plans at every price; equilibrium is the price and quantity that make those plans compatible.
DistinguishOwn-price changes move along a curve; other influences shift it.
AdjustShortages raise price; surpluses lower it.
SolveSet quantity demanded equal to quantity supplied.