SME
Grade 11 Science · Problem type
A lever
Use this for “A 600 N load sits 0.4 m from the fulcrum, and you push 1.6 m from it. What is the mechanical advantage, and what effort lifts it?”
Diagram
Ideal MA = effort arm/load arm = 1.6/0.4 = 4
Effort = load/MA = 600/4 = 150 N
Balanced when effort × effort arm = load × load arm.
This is an example. Type your own values to start a new problem.
FE (N)
×
LE (m)
=
FL (N)
×
LL (m)
MA
Mechanical advantage
calculated
Formulas
MA = LE/LL
4 = 1.6/0.4
FE = FL/MA
150
=
600
4
Assumptions
•
A lever balances when effort × effort arm = load × load arm.
•
The ideal mechanical advantage is the effort arm over the load arm: a long effort arm means less force.
•
Less force, more distance: the work you put in is the work done on the load.
Step-by-step
WE KNOW
FL = 600 N, LE = 1.6 m, LL = 0.4 m
FIND
mechanical advantage (MA), effort (FE)
Step 1 · Find mechanical advantage (MA)
Use MA = LE/LL
Effort arm over load arm.
MA = 1.6/0.4
MA = 4
Step 2 · Find effort (FE)
Use FE = FL/MA
An ideal machine divides the load by its mechanical advantage.
FE
=
600
4
FE = 150 N
Check
Put the numbers back in. Both sides should match.
4 = 1.6/0.4 ✓
150
=
600
4
✓
Topic check
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