Class 11 Gravitation worksheet

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. 1.

   The gravitational force between two bodies is 136 N. If the distance between them is reduced to 1/2, the force becomes:

   1. 34 N
   2. 272 N
   3. 136 N
   4. 544 N

   Answer

   (d) 544 N

   F ∝ 1/r²

2. 2.

   A planet has 5 times the mass and the same radius as the earth. The acceleration due to gravity on its surface is (g on earth = 10 m/s²):

   1. 50 m/s²
   2. 2 m/s²
   3. 51 m/s²
   4. 49 m/s²

   Answer

   (a) 50 m/s²

   g = GM/R², so g′ = g × m/r²

3. 3.

   A planet has 18 times the mass and 2 times the radius of the earth. Its escape speed is how many times the earth's?

   1. 9
   2. 12
   3. 36
   4. 3

   Answer

   (d) 3

   vₑ = √(2GM/R) ∝ √(M/R)

Section B · short answer

1. 4.

   A body has a mass of 46 kg. Find its mass and its weight on a planet where g is half of the earth's (g there = 5 m/s²). What is its weight on the earth? (Take g = 10 m/s².)

   Answer

   Mass 46 kg; weight 230 N; on the earth 460 N

   mass does not change; weight = mg

2. 5.

   At what height above the earth's surface does g become 1/16 of its value at the surface? (R = 6400 km)

   Answer

   19,200 km (= 3R)

   R²/(R + h)² = 1/16, so R + h = 4R

Section C · long answer

1. 6.

   A 1900 kg satellite orbits at a height of 24R above the earth's surface (R = 6.4 × 10⁶ m, g = 10 m/s²). Find (a) g at that height, (b) its orbital speed, (c) its period (π = 22/7), (d) its kinetic energy.

   Answer

   (a) 0.016 m/s²; (b) 1,600 m/s; (c) 6.29 × 10⁵ s; (d) 2.43 × 10⁹ J

   v = √(gR²/(R + h)) = 8000/√25; T = 2π(R + h)/v

Fresh sheets for your child

In the app, every Gravitation 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.

Coming soon for Android and iPhone.

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