Fisika kelas 10 | Hukum Gravitasi Newton

Introduction

This tutorial covers Newton's law of gravitation, a fundamental concept in physics that explains the force of attraction between two masses. Understanding this law is essential not only for physics students but also for anyone interested in how gravity influences everyday life. By the end of this guide, you will grasp the concept of gravitational force and how to apply the gravitational field equation to practical problems.

Step 1: Understand the Concept of Gravitational Force

Gravitational force is the attraction that exists between any two masses. Here are the key points to understand:

• Definition: Gravitational force is a universal force that pulls objects towards each other.

• Newton's Law of Gravitation: The force of gravity between two objects can be calculated using the formula:

  [ F = G \frac{m_1 m_2}{r^2} ]

  Where:

  • ( F ) is the gravitational force.
  • ( G ) is the gravitational constant (( 6.674 \times 10^{-11} , \text{N m}^2/\text{kg}^2 )).
  • ( m_1 ) and ( m_2 ) are the masses of the objects.
  • ( r ) is the distance between the centers of the two masses.

• Practical Tip: Remember that the gravitational force increases with mass and decreases with the square of the distance.

Step 2: Apply the Gravitational Field Equation

To solve physical problems involving gravity, you can use the gravitational field concept, which is defined as the force per unit mass experienced by a small test mass placed in the field.

• Gravitational Field Formula:

  [ g = \frac{F}{m} ]

  Where:

  • ( g ) is the gravitational field strength.
  • ( F ) is the gravitational force.
  • ( m ) is the mass experiencing the force.

• Real-World Application: For example, on Earth, the gravitational field strength is approximately ( 9.81 , \text{m/s}^2 ). This means every kilogram of mass experiences a force of about 9.81 Newtons due to gravity.

• Common Pitfall: Be careful with the units you use. Ensure you convert masses into kilograms and distances into meters for accurate calculations.

Step 3: Solve Practical Problems

Now that you have a grasp of the concepts, let's apply them to solve some practical problems:

1. Calculate the Force Between Two Objects:

   • Given two masses, ( m_1 = 5 , \text{kg} ) and ( m_2 = 10 , \text{kg} ), separated by a distance of 2 meters, calculate the gravitational force.

   • Use the formula:

     [ F = G \frac{m_1 m_2}{r^2} ]

     Substitute the values:

     [ F = 6.674 \times 10^{-11} \frac{5 \times 10}{2^2} = 8.3425 \times 10^{-10} , \text{N} ]

2. Determine the Gravitational Field Strength:

   • Using the force calculated above and the mass ( m = 5 , \text{kg} ), find ( g ).

   • Apply the formula:

     [ g = \frac{F}{m} = \frac{8.3425 \times 10^{-10}}{5} = 1.6685 \times 10^{-10} , \text{m/s}^2 ]

Conclusion

In this tutorial, you learned about Newton's law of gravitation, how to calculate gravitational forces, and how to apply the gravitational field equation in practical scenarios. Understanding these concepts is crucial for further studies in physics and can enhance your comprehension of the natural world.

Next, consider exploring topics such as orbital mechanics or the effects of gravity on different celestial bodies for a deeper understanding of gravitational principles. Happy learning!