Solving for One Variable in Terms of Others
In many applied problems, an equation may involve several variables, but you need to solve for just one of them in terms of the others. This process is essential in science, engineering, and everyday life. In general, the approach depends on whether the equation is linear or quadratic (in the variable of interest), or if it can be rearranged to match one of those types.
Ideal Gas Law (Chemistry/Physics)
Equation:
where
is the pressure, is the volume, is the number of moles of gas, is the universal gas constant, is the temperature.
Goal: Solve for
Solution
- Since the equation is linear inPerimeter of a Rectangle (Everyday Geometry)
Equation:
where
is the perimeter of a rectangle, is the length, is the width.
Goal: Solve for
Solution
- SubtractProjectile Motion (Physics/Engineering)
Equation (vertical position):
where
is the time (in seconds), is the initial velocity, is the initial height, is the constant reflecting gravitational acceleration (ft/s ).
Goal: Solve for
Solution
- Rewrite the equation to set it equal to zero:Lens Formula (Optics)
Equation:
where
is the focal length of the lens, is the distance from the lens to the object, is the distance from the lens to the image.
Goal: Solve for
Solution
- IsolatePeriod of a Pendulum (Physics)
The period of a simple pendulum is approximately given by
where
is the period (in seconds), is the length of the pendulum (in meters), is the acceleration due to gravity (in m/s ).
Goals:
- (A) Solve for
in terms of and . - (B) Solve for
in terms of and .
Solution
- **Goal A:** Square both sides and solve forPythagorean Theorem (Geometry/Engineering)
Equation:
where
and are the legs of a right triangle, is the hypotenuse.
Goal: Solve for