Automotive Technology (47.0604) T-Chart
Apply and extend the properties of exponents to solve
Calculate electrical power and horsepower
problems with rational exponents
Program Task: Use a dynamometer.
PA Core Standard: CC.2.1.HS.F.1
Description: Apply and extend the properties of exponents to solve
problems with rational exponents.
Program Associated Vocabulary:
Math Associated Vocabulary:
TORQUE, ROTATIONAL VELOCITY, POWER,
SIMPLIFY NUMERICAL EXPRESSION, TERM
HORSEPOWER, LB-FT, HP, RPM
Program Formulas and Procedures:
Formulas and Procedures:
A dynamometer is a device used to measure force, torque,
or power. For example, the power produced by an engine or
Do all operations in PARENTHESIS. Start with the
motor can be calculated by simultaneously measuring
torque and rotational speed.
Evaluate all EXPONENTS.
The formula for this calculation is:
Do MULTIPLICATION and DIVISION in order
from left to right.
P = power (horsepower)
τ = torque (pound-feet)
Do ADDITION and SUBTRACTION in order from
ω = rotational velocity (revolutions per minute)
left to right.
A mechanic uses a dynamometer to measure torque and
One way to remember the order of operations is:
rotational speed. The engine is running with 300 ft. lbs. of
torque and 6500 revolutions per minute. What is the
Please Excuse My Dear Aunt Sally.
horsepower of the engine? (Round to nearest whole number)
Remembering that my and dear go together since they both describe
Aunt Sally who is one person.
T × w
300 × 6500
(7 + 3)
- 21÷7 + 10(2) =
- 21÷7 + 10(2) Parentheses
P = 371 HP
100 - 21÷7 + 10(2) Exponents
100 – 3 +20 Multiplication and Division
97 + 20 Addition and Subtraction
A mechanic uses a dynamometer to simulate an automobile
being driven over a mountain pass at 8325 feet in altitude.
The engine is rated at 255 hp. at 5200 rpm. What is the loss
in horsepower due to elevation?
HP loss = Elevation in feet ÷ 1000 × 0.03 × Sea Level HP
HP loss = 8325 ÷ 1000 × 0.03 × 255
HP loss = 8.325 × 0.03 × 255
HP loss = 0.24975 × 255
HP loss = 63.69 HP
Originated June 2009
Reviewed June 2015