How do we know that, according to Newton's Second Law, the force and the acceleration acting on an object are proportional? A:

Question

12. When you have a force acting on an object in a specific direction, Newton's Second Law states that the acceleration on that object will be in the same direction of the force. Given this information, can you explain what would happen to an object that is moving towards the right at a constant speed when you put a force on it towards the left? Give your reasoning for this answer. A:
13. What happens to the acceleration of an object when you increase the mass? Decrease the mass? What does this mean about the relationship between mass and acceleration?
A:
14. Will an object move that has two forces acting upon it in an equal, but opposite manner?
Which of Newton's laws is this? A:third law
15. What effect does air resistance have on falling objects, and why does the acceleration due to gravity have to be measured in an airless tube? A:

Answer 1

Let's go through your questions one by one.

12. According to Newton's Second Law (F = ma), when a force is applied to an object that is already moving towards the right at a constant speed, the direction of the net force will determine the result. If you apply a force towards the left, this will create a net force in that direction, opposing the object's initial motion. As a result, the object will experience a leftward acceleration. If the leftward force is greater than the inertia of the object (the tendency to maintain its state of motion), the object will gradually slow down and eventually start moving to the left. If the leftward force is equal to the inertia (meaning no net force), the object's speed will remain constant. If the leftward force is less than what is needed to change the motion, it will decelerate but continue to move to the right.

13. According to Newton's Second Law, if we keep the force constant and increase the mass of the object, the acceleration (a) will decrease, since \( a = \frac{F}{m} \). Conversely, if you decrease the mass while keeping the same force, the acceleration will increase. This indicates an inverse relationship between mass and acceleration—greater mass results in less acceleration for a given force, and lower mass results in greater acceleration. Hence, mass and acceleration are inversely proportional under constant force conditions.

14. If an object has two forces acting upon it that are equal in magnitude but opposite in direction, these forces will cancel each other out, resulting in a net force of zero. Therefore, the object will not move (or will maintain its state of motion if it was already moving). This situation illustrates Newton's First Law, which states that an object at rest stays at rest, and an object in motion continues in motion at the same speed and in the same direction unless acted upon by a net external force.

15. Air resistance, or drag, affects falling objects by opposing the force of gravity, which results in a reduced net acceleration. When an object falls through the air, it experiences an upward force of air resistance that acts against the downward gravitational force. In a vacuum or airless tube, this air resistance is eliminated, allowing objects to fall only under the influence of gravity. This means when measuring the acceleration due to gravity, it's crucial to conduct the experiment in an environment where other forces (like air resistance) do not interfere, leading to accurate measurement of gravitational acceleration (approximately \(9.81 , \text{m/s}^2\) near the Earth's surface).