Identify how Earth's gravitational field strength changes with increasing distance.It decreasesIt increasesIt stays the sameI'm not sure

Understanding Earth's Gravitational Field Strength

1. Definition of Gravitational Field Strength: Gravitational field strength ($g$) is defined as the force of gravity experienced per unit mass at a point in space. Near the Earth's surface, it is approximately $9.81 \, \text{m/s}^2$.

2. Relation to Distance: According to the law of universal gravitation, the gravitational force ($F$) between two masses ($m_1$ and $m_2$) is given by: $F = \frac{G \cdot m_1 \cdot m_2}{r^2}$ where $G$ is the gravitational constant and $r$ is the distance between the centers of the two masses.

3. Gravitational Field Strength Formula: The gravitational field strength at a distance $r$ from the center of the Earth is expressed as: $g = \frac{G \cdot M}{r^2}$ where $M$ is the mass of the Earth.

Analysis of the Change in Gravitational Field Strength

1. Distance Increase and Gravitational Strength: As the distance $r$ from the center of the Earth increases, the value of $r^2$ becomes larger. Consequently, the gravitational field strength $g$ decreases inversely with the square of the distance.

2. Implication: This means that the further you move away from the Earth (i.e., increasing distance $r$), the weaker the gravitational pull, thus leading to a decrease in gravitational field strength.

Final Answer

The correct answer is It decreases.