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Class 9 · Science worksheet

The Geometry of Power – Advanced Simple Machines (Advanced)

CBSE Science. Optional Advanced level: wheel and axle, mechanical advantage and efficiency, gear trains, tension, two masses over a pulley. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.

Open a printable sample sheet Cheat sheet: formulas and key points

Sample questions

Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.

Section A · multiple choice

1.
A steering wheel of radius 16 cm turns an axle of radius 2 cm. The mechanical advantage is:
1. 0.13
2. 14
3. 18
4. 8
Answer
(d) 8
MA = radius of wheel ÷ radius of axle = 16 ÷ 2
2.
A wheel and axle has a wheel 19 times the radius of its axle. The effort needed on the wheel to overcome a load of 2,000 N is (ideal machine): (Give the answer to 2 decimal places where needed.)
1. 38,000 N
2. 111.11 N
3. 105.26 N
4. 5.54 N
Answer
(c) 105.26 N
effort = load ÷ MA = 2,000 ÷ 19
3.
A machine lifts an 80 N load through 4 m while an effort of 100 N moves through 4 m. Its efficiency is:
1. 95%
2. 81%
3. 125%
4. 80%
Answer
(d) 80%
η = output work ÷ input work × 100 = 320 J ÷ 400 J × 100

Section B · short answer

4.
A wheel of radius 21 cm is fixed to an axle of radius 19 mm. What effort on the wheel lifts a 1,500 N load hanging from the axle (ideal machine)? (Give the answer to 2 decimal places where needed.)
Answer
135.71 N
MA = 210 mm ÷ 19 mm; effort = 1,500 ÷ MA
5.
A wheel and axle must have a mechanical advantage of 6. If the axle's radius is 3 cm, what must the wheel's radius be?
Answer
18 cm
R = MA × r = 6 × 3

Section C · long answer

6.
A truck's steering needs a turning force of 2,100 N at the axle. The steering wheel has a radius of 16 cm and the axle 2 cm. (a) Find the mechanical advantage. (b) What effort is needed on the rim of an ideal steering wheel? (c) What effort is needed if the steering is only 60% efficient? (Give the answer to 2 decimal places where needed.)
Answer
(a) 8; (b) 262.5 N; (c) 437.5 N
(a) 16 ÷ 2; (b) 2,100 ÷ 8; (c) 262.5 × 100 ÷ 60

Fresh sheets for your child

In the app, every The Geometry of Power – Advanced Simple Machines (Advanced) sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.

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