Content Standard
The efficiencyof simple and compound
machines can be improved by applying basic
physics principles.
MELC Most Essential Learning
Competency
Explain the characteristics of efficient simple
and compound machines.
3.
OBJECTIVES
1. Differentiate betweensimple and compound
machines.
2. Explain how translational and rotational
motions apply to machine efficiency.
3. Analyze how basic physics principles improve
the efficiency of machines.
4. Design and build a working prototype of a
compound machine using concepts of motion
and efficiency.
Activity: Scenario Challenge
•Two students are using different
machines to lift the same load.
One is sweating a lot while the
other seems relaxed. Why do
you think one machine is more
efficient than the other?
6.
Basic Principles Appliedto Simple
and Compound Machines
1. Mechanical Advantage (MA) :
- Tells how many times a machine multiplies the input force.
Formula: MA = Output Force (Load) / Input Force (Effort)
Example: Simple Machine: Lever – A seesaw allows a small child to lift a
heavier adult by adjusting the position.
Sample Problem:
A lever lifts a 200 N load using only 50 N of effort.
MA = 200 N / 50 N = 4
Answer: The mechanical advantage is 4.
7.
Basic Principles Appliedto Simple
and Compound Machines
2. Ideal Mechanical Advantage (IMA)
- Mechanical advantage without considering friction.
Formula: IMA = Length of Ramp / Height of Ramp
Example: Simple Machine: Inclined Plane – Makes it
easier to load cargo into a truck.
Sample Problem:
A ramp is 6 m long and 2 m high.
IMA = 6 / 2 = 3
Answer: The ideal mechanical advantage is 3.
8.
Basic Principles Appliedto Simple
and Compound Machines
3. Actual Mechanical Advantage (AMA)
Real-world MA, considering friction.
Formula: AMA = Load (Output Force) / Effort (Input Force)
Example: Compound Machine: Wheelbarrow – Combines
wheel and lever to move heavy loads.
Sample Problem:
A person uses 80 N of force to push a wheelbarrow
carrying a 240 N load.
AMA = 240 / 80 = 3
Answer: AMA = 3
9.
Basic Principles Appliedto Simple
and Compound Machines
4. Efficiency
- Shows how well a machine converts input work into
output work.
Formula: Efficiency (%) = (AMA / IMA) × 100
Example: Compound Machine: Scissors – Combines levers
and wedges, efficiency depends on sharpness.
Sample Problem:
A machine has an IMA of 4 and AMA of 3.
Efficiency = (3 / 4) × 100 = 75%
Answer: The machine is 75% efficient.
10.
Basic Principles Appliedto Simple
and Compound Machines
5. Work
- Work is done when a force is applied over a distance.
Formula: Work = Force × Distance
- Example: Simple Machine: Pulley – Pulling the rope
does work by lifting the object.
Sample Problem:
- You apply a 50 N force to lift a box 2 m high using a
pulley.
- Work = 50 × 2 = 100 J
- Answer: Work done = 100 joules
11.
Basic Principles Appliedto Simple
and Compound Machines
6. Direction Change of Force
- Definition: Some machines allow force to be applied
in a more convenient direction.
Formula: No formula
Example: Simple Machine: Fixed Pulley – Pulling down
on a rope to lift an object up.
Sample Problem:
- Conceptual: Pulling a 10 N force down lifts a 10 N
object up — force direction changed, not magnitude.
12.
Basic Principles Appliedto Simple
and Compound Machines
7. Force and Distance Trade-Off
Less force = more distance, and vice versa.
Formula: Effort Force × Effort Distance = Load Force × Load
Distance
Example: Simple Machine: Inclined Plane – Using a longer
ramp makes it easier to lift.
Sample Problem:
Effort = 100 N, distance = 3 m, Load = 300 N, height = 1 m
100 × 3 = 300 × 1
Answer: The work input equals work output.
![Physics in daily life.GENSCI Lesson1 [Autosaved].pptx](https://cdn.slidesharecdn.com/ss_thumbnails/physicsindailylife-250622004038-2bd1a474-thumbnail.jpg?width=640&height=640&fit=bounds)
