PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
PHS 104A Pulleys &
Mechanical Advantage
Practice Questions 2026–2027 | 110 Original Problems with Worked Solutions
Independent study material, not an official PHS 104A examination. Assume massless
inextensible ropes, frictionless pulleys, and g = 9.8 m/s² unless a problem states otherwise.
A fixed pulley only changes force direction; ideal mechanical advantage equals the number
of supporting rope segments for a movable load.
Formula Reference
• Weight W = mg; force in newtons (N), mass in kilograms (kg).
• Ideal mechanical advantage IMA = load force / effort force = number of load-supporting
rope segments.
• Actual mechanical advantage AMA = measured load force / measured effort force.
• Efficiency (%) = (AMA / IMA) × 100 = (useful output work / input work) × 100.
• Ideal displacement ratio: effort distance / load distance = IMA.
• Work = force × displacement along force; power = work / time.
• For two hanging masses on an ideal Atwood machine: a = (m₂ − m₁)g / (m₁ + m₂), when m₂
> m₁; tension T = 2m₁m₂g/(m₁+m₂).
Independent educational practice | Page 1
,PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
Ideal Pulley Forces
Question 1. An ideal block-and-tackle supports a 40 N load with 2 rope segments.
What effort force is required?
A. 40 N
B. 20 N
C. 80 N
D. 40 N
Correct Answer: B. 20 N
Worked Solution: IMA = 2; F = 40/2 = 20 N.
Why the Other Options Are Incorrect: A (40 N) does not match the governing
relationship or the calculated result. C (80 N) does not match the governing
relationship or the calculated result. D (40 N) does not match the governing
relationship or the calculated result.
Question 2. An ideal block-and-tackle supports a 60 N load with 3 rope segments.
What effort force is required?
A. 60 N
B. 40 N
C. 20 N
D. 180 N
Correct Answer: C. 20 N
Worked Solution: IMA = 3; F = 60/3 = 20 N.
Why the Other Options Are Incorrect: A (60 N) does not match the governing
relationship or the calculated result. B (40 N) does not match the governing
relationship or the calculated result. D (180 N) does not match the governing
relationship or the calculated result.
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,PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
Question 3. An ideal block-and-tackle supports a 80 N load with 4 rope segments.
What effort force is required?
A. 320 N
B. 80 N
C. 40 N
D. 20 N
Correct Answer: D. 20 N
Worked Solution: IMA = 4; F = 80/4 = 20 N.
Why the Other Options Are Incorrect: A (320 N) does not match the governing
relationship or the calculated result. B (80 N) does not match the governing
relationship or the calculated result. C (40 N) does not match the governing
relationship or the calculated result.
Question 4. An ideal block-and-tackle supports a 100 N load with 5 rope segments.
What effort force is required?
A. 20 N
B. 500 N
C. 100 N
D. 40 N
Correct Answer: A. 20 N
Worked Solution: IMA = 5; F = 100/5 = 20 N.
Why the Other Options Are Incorrect: B (500 N) does not match the governing
relationship or the calculated result. C (100 N) does not match the governing
relationship or the calculated result. D (40 N) does not match the governing
relationship or the calculated result.
Question 5. An ideal block-and-tackle supports a 120 N load with 6 rope segments.
What effort force is required?
A. 40 N
B. 20 N
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, PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
C. 720 N
D. 120 N
Correct Answer: B. 20 N
Worked Solution: IMA = 6; F = 120/6 = 20 N.
Why the Other Options Are Incorrect: A (40 N) does not match the governing
relationship or the calculated result. C (720 N) does not match the governing
relationship or the calculated result. D (120 N) does not match the governing
relationship or the calculated result.
Question 6. An ideal block-and-tackle supports a 140 N load with 7 rope segments.
What effort force is required?
A. 140 N
B. 40 N
C. 20 N
D. 980 N
Correct Answer: C. 20 N
Worked Solution: IMA = 7; F = 140/7 = 20 N.
Why the Other Options Are Incorrect: A (140 N) does not match the governing
relationship or the calculated result. B (40 N) does not match the governing
relationship or the calculated result. D (980 N) does not match the governing
relationship or the calculated result.
Question 7. An ideal block-and-tackle supports a 160 N load with 8 rope segments.
What effort force is required?
A. 1280 N
B. 160 N
C. 40 N
D. 20 N
Correct Answer: D. 20 N
Worked Solution: IMA = 8; F = 160/8 = 20 N.
Why the Other Options Are Incorrect: A (1280 N) does not match the governing
relationship or the calculated result. B (160 N) does not match the governing
Independent educational practice | Page 4
PHS 104A Pulleys &
Mechanical Advantage
Practice Questions 2026–2027 | 110 Original Problems with Worked Solutions
Independent study material, not an official PHS 104A examination. Assume massless
inextensible ropes, frictionless pulleys, and g = 9.8 m/s² unless a problem states otherwise.
A fixed pulley only changes force direction; ideal mechanical advantage equals the number
of supporting rope segments for a movable load.
Formula Reference
• Weight W = mg; force in newtons (N), mass in kilograms (kg).
• Ideal mechanical advantage IMA = load force / effort force = number of load-supporting
rope segments.
• Actual mechanical advantage AMA = measured load force / measured effort force.
• Efficiency (%) = (AMA / IMA) × 100 = (useful output work / input work) × 100.
• Ideal displacement ratio: effort distance / load distance = IMA.
• Work = force × displacement along force; power = work / time.
• For two hanging masses on an ideal Atwood machine: a = (m₂ − m₁)g / (m₁ + m₂), when m₂
> m₁; tension T = 2m₁m₂g/(m₁+m₂).
Independent educational practice | Page 1
,PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
Ideal Pulley Forces
Question 1. An ideal block-and-tackle supports a 40 N load with 2 rope segments.
What effort force is required?
A. 40 N
B. 20 N
C. 80 N
D. 40 N
Correct Answer: B. 20 N
Worked Solution: IMA = 2; F = 40/2 = 20 N.
Why the Other Options Are Incorrect: A (40 N) does not match the governing
relationship or the calculated result. C (80 N) does not match the governing
relationship or the calculated result. D (40 N) does not match the governing
relationship or the calculated result.
Question 2. An ideal block-and-tackle supports a 60 N load with 3 rope segments.
What effort force is required?
A. 60 N
B. 40 N
C. 20 N
D. 180 N
Correct Answer: C. 20 N
Worked Solution: IMA = 3; F = 60/3 = 20 N.
Why the Other Options Are Incorrect: A (60 N) does not match the governing
relationship or the calculated result. B (40 N) does not match the governing
relationship or the calculated result. D (180 N) does not match the governing
relationship or the calculated result.
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,PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
Question 3. An ideal block-and-tackle supports a 80 N load with 4 rope segments.
What effort force is required?
A. 320 N
B. 80 N
C. 40 N
D. 20 N
Correct Answer: D. 20 N
Worked Solution: IMA = 4; F = 80/4 = 20 N.
Why the Other Options Are Incorrect: A (320 N) does not match the governing
relationship or the calculated result. B (80 N) does not match the governing
relationship or the calculated result. C (40 N) does not match the governing
relationship or the calculated result.
Question 4. An ideal block-and-tackle supports a 100 N load with 5 rope segments.
What effort force is required?
A. 20 N
B. 500 N
C. 100 N
D. 40 N
Correct Answer: A. 20 N
Worked Solution: IMA = 5; F = 100/5 = 20 N.
Why the Other Options Are Incorrect: B (500 N) does not match the governing
relationship or the calculated result. C (100 N) does not match the governing
relationship or the calculated result. D (40 N) does not match the governing
relationship or the calculated result.
Question 5. An ideal block-and-tackle supports a 120 N load with 6 rope segments.
What effort force is required?
A. 40 N
B. 20 N
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, PHS 104A | PULLEYS & MECHANICAL ADVANTAGE | 2026–2027
C. 720 N
D. 120 N
Correct Answer: B. 20 N
Worked Solution: IMA = 6; F = 120/6 = 20 N.
Why the Other Options Are Incorrect: A (40 N) does not match the governing
relationship or the calculated result. C (720 N) does not match the governing
relationship or the calculated result. D (120 N) does not match the governing
relationship or the calculated result.
Question 6. An ideal block-and-tackle supports a 140 N load with 7 rope segments.
What effort force is required?
A. 140 N
B. 40 N
C. 20 N
D. 980 N
Correct Answer: C. 20 N
Worked Solution: IMA = 7; F = 140/7 = 20 N.
Why the Other Options Are Incorrect: A (140 N) does not match the governing
relationship or the calculated result. B (40 N) does not match the governing
relationship or the calculated result. D (980 N) does not match the governing
relationship or the calculated result.
Question 7. An ideal block-and-tackle supports a 160 N load with 8 rope segments.
What effort force is required?
A. 1280 N
B. 160 N
C. 40 N
D. 20 N
Correct Answer: D. 20 N
Worked Solution: IMA = 8; F = 160/8 = 20 N.
Why the Other Options Are Incorrect: A (1280 N) does not match the governing
relationship or the calculated result. B (160 N) does not match the governing
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