When a scale is used to weigh an object on Earth, it measures the gravitational force that pulls on the object. The unit for the force of gravity pulling on an object is the newton (N). A student uses a scale to measure the force of gravity on five different objects. The masses of the objects are 20, 40, 60, 80, and 100 grams. She plotted her data on the graph shown below.
What does the data show?
A. An object gains mass when the gravitational force on Earth remains the same.
B. The smaller the mass of an object, the greater the gravitational pull exerted on it by Earth.
C. An object loses mass when the gravitational force on Earth remains the same.
D. The greater the mass of an object, the greater the gravitational pull exerted on it by Earth.
The Correct Answer and Explanation is:
The correct answer is D. The greater the mass of an object, the greater the gravitational pull exerted on it by Earth.
Explanation:
When a scale is used to weigh an object on Earth, it measures the gravitational force acting on that object. This force, often referred to as weight, is calculated using the equation:
[ F = m \cdot g ]
where:
- ( F ) is the force (weight) in newtons (N),
- ( m ) is the mass of the object in kilograms (kg),
- ( g ) is the acceleration due to gravity, approximately ( 9.81 \, \text{m/s}^2 ) on Earth.
In the scenario described, the student measured the masses of five different objects: 20, 40, 60, 80, and 100 grams. When she plotted this data on a graph, she would see a direct correlation between the mass of each object and the force of gravity acting on it.
As the mass of an object increases, the weight (force due to gravity) also increases. For instance, an object with a mass of 100 grams will weigh more than an object with a mass of 20 grams, assuming the gravitational field strength remains constant. This relationship is linear, indicating that for every increase in mass, there is a proportional increase in the gravitational force.
Option A is incorrect because an object does not gain mass simply because of the gravitational force acting on it; mass is an intrinsic property of matter. Option B is incorrect as it suggests an inverse relationship between mass and gravitational force, which contradicts the established principles of physics. Option C is also incorrect because mass does not change due to gravitational force; it remains constant unless physically altered.
Therefore, the data illustrates the fundamental principle of physics: the greater the mass of an object, the greater the gravitational pull exerted on it by Earth, which is consistent with the laws of motion and gravity.