Worksheets › Class 9 › Work, Energy, and Simple Machines
Class 9 Work, Energy, and Simple Machines worksheet
CBSE Science. Work, kinetic and potential energy, power, kWh; levers, pulleys and inclined planes. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
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 force of 35 N moves an object 22 m in the direction of the force. The work done is:
- 1.59 J
- 57 J
- 1,540 J
- 770 J
Answer
(d) 770 J
W = F × s = 35 × 22
- 2.
The kinetic energy of a 51 kg body moving at 20 m/s is:
- 10,200 J
- 20,400 J
- 510 J
- 1,020 J
Answer
(a) 10,200 J
½mv² = ½ × 51 × 400
- 3.
The potential energy of a 16 kg object at a height of 2 m is (g = 9.8 m/s²):
- 156.8 J
- 32 J
- 176.4 J
- 313.6 J
Answer
(d) 313.6 J
mgh = 16 × 9.8 × 2
Section B · short answer
- 4.
Find the work done in lifting a 48 kg load through a height of 16 m. Take g = 9.8 m/s².
Answer
7,526.4 J
W = mgh = 48 × 9.8 × 16
- 5.
A 29 kg body speeds up from 2 m/s to 10 m/s. Find the work done on it. (Give the answer to 2 decimal places where needed.)
Answer
1,392 J
work = change in KE = ½ × 29 × (100 − 4)
Section C · long answer
- 6.
A family uses 6 bulbs of 60 W for 4 hours a day and a 75 W fan for 6 hours a day. Find the electricity used in 30 days and the cost at Rs 5 per unit.
Answer
56.7 kWh; Rs 283.5
(6 × 60 × 4 + 75 × 6) × 30 ÷ 1000 kWh
Fresh sheets for your child
In the app, every Work, Energy, and Simple Machines 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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