GCSE Engineering, Systems. Usually met in years 9 to 11.
Calculate gear ratios, output speeds, moments, mechanical advantage and efficiency.
What you practise
Gear ratios and output speed
Moments about a pivot
Mechanical advantage, compound gears and efficiency
Starts with a single pair of gears and builds to compound trains and efficiency. Practice moves up a level when a round goes well and down when it does not.
Sample questions
Each sample comes with the method and the reason every wrong option is wrong. Real practice rounds are ten questions at your level.
Sample question, level 2 of 5
A motor turns at 160 rpm through a gear ratio of 8:1. What is the output speed?
160 rpm
0.05 rpm
152 rpm
1,280 rpm
20 rpm
Show the answer and method
Answer: E, 20 rpm
The method: Output speed = input speed ÷ gear ratio = 160 ÷ 8 = 20 rpm.
Why the other options are wrong:
A, 160 rpm: The speed changes through the gears.
B, 0.05 rpm: The division is upside down.
C, 152 rpm: The ratio was subtracted.
D, 1,280 rpm: The speed was multiplied by the ratio. A ratio of more than 1 slows the output down: divide.
Sample question, level 4 of 5
A lever lifts a load of 130 N with an effort of 65 N. What is its mechanical advantage?
