Question

physics
inmotion
unit 3a
newtons laws overview
gpb.org/physics-motion
note - taking guide and questions to consider
name:
date:
answer the following.

1. if two different net forces are applied to the same object at different times, which one will cause the object

to accelerate at a greater rate - the larger or smaller net force?

1. what are the two types of motion an object can experience when acted upon by balanced forces?
2. what is the equation for newtons second law?
3. define newtons third law in your own words, and give an example.
4. explain the action - reaction pair involved when a person walks down a sidewalk.

Explanation:

• Question 7: According to Newton's second law \(F = ma\) (where \(F\) is the net force, \(m\) is the mass of the object, and \(a\) is the acceleration), when \(m\) is constant (same object), \(a=\frac{F}{m}\). So, a larger net force will cause a greater acceleration.
• Question 8: When balanced forces (\(\sum F = 0\)) act on an object, from Newton's first law (an object at rest stays at rest and an object in motion stays in motion with a constant velocity unless acted upon by an un - balanced force), the object can be at rest (zero velocity) or in uniform motion (constant velocity, which means zero acceleration as \(a = \frac{\Delta v}{\Delta t}\) and \(\Delta v=0\)).
• Question 9: Newton's second law is mathematically expressed as \(F_{net}=ma\), where \(F_{net}\) is the net force acting on an object, \(m\) is the mass of the object, and \(a\) is the acceleration of the object.
• Question 10: Newton's third law states that for every action, there is an equal and opposite reaction. For example, when you push on a wall (\(F_{action}\)), the wall pushes back on you (\(F_{reaction}\)) with the same magnitude but in the opposite direction.
• Question 11: When a person walks down a sidewalk, the action force is the force that the person's foot exerts on the sidewalk (pushing the sidewalk backward). The reaction force is the force that the sidewalk exerts on the person's foot (pushing the person forward).

Answer:

1. The larger net force. Since \(F = ma\) (\(m\) is constant for the same object), \(a\) is directly proportional to \(F\).
2. The object can be at rest (zero velocity) or in uniform motion (constant velocity).
3. \(F_{net}=ma\)
4. Newton's third law: For every action, there is an equal and opposite reaction. Example: When you push a book on a table (\(F_{action}\)), the book pushes back on your hand (\(F_{reaction}\)).
5. Action: Foot pushes sidewalk backward. Reaction: Sidewalk pushes foot (and thus the person) forward.