Gravitation Work Energy and Sound (Class 9)

What this worksheet covers

This is an eighteen-question practice worksheet on gravitation, work, energy and sound for Class 9, written to the pattern of the SOF National Science Olympiad (NSO). It carries 24 marks and is designed to be attempted in 45 minutes, split across three sections — Scientific Reasoning, Applying What You Know and Achievers Section. Every question is multiple choice with exactly one correct option, and every one comes with a fully worked solution rather than just an answer key — so a child who gets one wrong can see where the reasoning went astray instead of only learning that it did.

Skills your child practises

• Applied problem-solving on gravitation, work, energy and sound at Class 9 level
• Working accurately against a time limit, as the real paper demands
• Scientific Reasoning questions in the olympiad format
• Applying What You Know questions in the olympiad format
• Achievers Section questions in the olympiad format
• Reading worked solutions to find the step that went wrong

How to use it

1. 1There are 18 questions in this worksheet. All questions are compulsory.
2. 2Each question has four options (A), (B), (C) and (D). Exactly one option is correct.
3. 3Questions 1–15 carry 1 mark each. Questions 16–18 (Achievers Section) carry 3 marks each.
4. 4Take g = 10 m/s² unless stated otherwise. There is no negative marking.

Sample questions from this worksheet

A preview of what's inside Gravitation Work Energy and Sound (Class 9) — the PDF has the full set, and every question comes with a worked solution like these.

1. 1. According to the universal law of gravitation, the force between two bodies is _______.

   • AInversely proportional to the square of the distance between themcorrect
   • BDirectly proportional to the square of the distance between them
   • CIndependent of the distance between them
   • DInversely proportional to the product of their masses
   Solution: The law states F = G{m₁m₂/r²}: the force grows with the product of the masses but falls off as the square of the separation, so it is inversely proportional to r². Doubling the distance cuts the force to a quarter.

2. 2. The weight of a body of mass 10 kg on the surface of the earth (g = 9.8 m/s²) is _______.

   • A10 N
   • B9.8 N
   • C98 Ncorrect
   • D980 N
   Solution: Weight W = mg = 10 × 9.8 = 98 N. Weight is a force, so it is measured in newtons and not in kilograms.

3. 3. Assertion (A): A person can jump higher on the moon than on the earth.Reason (R): The mass of a person on the moon is one-sixth of the mass on the earth.

   • ABoth A and R are true and R is the correct explanation of A
   • BBoth A and R are true but R is not the correct explanation of A
   • CA is true but R is falsecorrect
   • DA is false but R is true
   Solution: The assertion is true: with the moon’s g about one-sixth of the earth’s, the same muscular energy lifts a person roughly six times as high. But the reason is false — mass does not change with location; it is the weight that becomes one-sixth. So A is true and R is false.