Class 10 Science
Gravitation Solutions
Premium solved exercise for Science & Technology Part 1. Learn mass, weight, Kepler’s laws, and numerical problems with our expert guidance.
Chapter Overview
Chapter 1: Gravitation introduces the universal force that keeps planets in orbit and objects grounded. We cover Newton's laws, Kepler's observations, and the critical distinction between mass and weight.
Exercise Questions & Answers
| Concept | Correct Unit | Correct Property |
|---|---|---|
| Mass | kg | Measure of inertia |
| Weight | N | Zero at centre |
| Acc. due to gravity | m/s² | Depends on height |
| Grav. constant (G) | N m²/kg² | Same in the entire universe |
Q2. Answer the following:
| Property | Mass | Weight |
|---|---|---|
| Definition | The amount of matter in an object. | The gravitational force acting on the object. |
| SI Unit | kg | Newton (N) |
| Formula | Scalar quantity | W = mg (Vector) |
| Location | Remains constant everywhere. | Changes depending on local gravity. |
- Law of Orbits: Every planet revolves around the Sun in an elliptical orbit, with the Sun at one of the foci.
- Law of Areas: The line joining the planet and the Sun sweeps equal areas in equal intervals of time.
- Law of Periods: The square of its period of revolution ($T^2$) is directly proportional to the cube of the mean distance ($r^3$) of a planet from the Sun: $T^2 \propto r^3$.
As we go inside the earth, the mass of the earth that contributes towards gravity decreases. At the exact centre, the mass of the earth "pulling" from all directions is balanced. Mathematically, in the formula $g = \frac{GM}{R^2}$, as we reach the centre, effective $M$ becomes zero because we are surrounded uniformly by mass. Thus, net acceleration due to gravity $g = 0$.
Question 5: Gravitation Numericals
- Height ($s$) = 5 m
- Time ($t$) = 5 s
- Initial velocity ($u$) = 0
5 = ½ × g × 25
10 = 25g
g = 10 / 25 = 0.4 m/s²
Final Answer: g = 0.4 m/s²
Mass remains same everywhere. So, Mass on Moon = 5 kg.
Gravity on moon is 1/6th of earth gravity.
Weight = 49 / 6 ≈ 8.17 N
Final Answer: Mass = 5 kg, Weight = 8.17 N
Project: Weight Calculator
Enter your weight on Earth to calculate your weight on the Moon and Mars!
| Planet | Weight Value (approx) |
|---|---|
| Moon (1/6g) | 10.00 kg |
| Mars (0.38g) | 22.80 kg |
Formula Hub
m = mass, g = acc. due to gravity
The base law of attraction.
Kepler's 3rd Law.
Chapter Quiz
Ready to test your knowledge on Gravitation?
Frequently Asked Questions
What is Free Fall?
The motion of an object where gravity is the only force acting on it is called free fall.
What is escape velocity?
The minimum speed needed for an object to escape Earth's gravitational pull for good. (11.2 km/s approx)
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