1. DIRECT VARIATION EQUATION: y = kx
(where x and y are variables and k is the constant)
EXAMPLES:
“weight varies directly with the distance”
w(eight) = k d(istance)
“distance is directly proportional to the Velocity”
d = kV
“price varies directly as weight”
p = kw

2. (Answers will be shown on the last slide.)
YOUR TURN!!
REMINDER: y = kx
Ex 1) The mass of a substance varies directly as the volume of the substance. If the mass of 2 L of the substance is 10 kg, what will be the volume of 35 kg of the substance?
Remember to find k first then do the equation again to answer the question.
Ex 2) The distance traveled by a car at a constant speed is directly proportional to the time spent traveling. If the car goes 75 km in 5 hrs, how far will it go in 7 hours?
(Answers will be shown on the last slide.)

3. (Answers will be shown on the last slide.)
REMINDER: y = kx
Ex 3) Under certain conditions the pressure of a gas varies directly as the temperature. When the pressure is 800 pascals, the temperature is 400 K. What is the temperature when the pressure is 400 pascals?
Remember to find k first then do the equation again to answer the question.
(Answers will be shown on the last slide.)

4. ANSWERS!
Ex 1) M = kV
10 = k2
k = 5
35 = 5V
7 = V
7 liters
Ex 2) D = kT
75 = k5
k = 15
D = 15(7)
D = 105
105 km
Ex 3) P = kT
800 = k400
k = 2
400 = 2T
T = 200
200 K