GED Science - S02.2v3
Physics > Newton's Laws > Concepts & Problems
Important Instructions
"Before starting the test, let's review the essential concepts of answering scientific experiment-based questions. Please read each question carefully and respond to all 20 questions within TIME LIMIT of 30 min.
Newton's Laws of Motion Formulas
1. Newton's First Law (Law of Inertia)
Concept: Objects in motion stay in motion, and objects at rest stay at rest unless acted upon by an external force.
Explanation: This law states that an object will not change its state of motion unless a force is applied, describing the concept of inertia.
2. Newton's Second Law (Law of Acceleration)
Formula: \( F = ma \)
Explanation: The force \( F \) acting on an object is equal to the mass \( m \) of the object multiplied by its acceleration \( a \). This formula quantifies the relationship between force, mass, and acceleration.
3. Newton's Third Law (Action and Reaction)
Concept: For every action, there is an equal and opposite reaction.
Explanation: This law states that forces always come in pairs. When one object exerts a force on a second object, the second exerts a force equal in magnitude and opposite in direction on the first.
Applications and Derived Formulas of Newton's Laws
1. Net Force on Inclined Planes
Formula: \( F_{\text{net}} = mg \sin \theta - f_k \)
Explanation: The net force \( F_{\text{net}} \) on an object sliding down an incline with angle \( \theta \) is the component of gravitational force down the incline \( mg \sin \theta \) minus the kinetic frictional force \( f_k \).
2. Frictional Force
Formula: \( f = \mu N \)
Explanation: The frictional force \( f \) is equal to the coefficient of friction \( \mu \) multiplied by the normal force \( N \). This formula is used to calculate resistance to motion due to friction.
3. Gravitational Force
Formula: \( F_g = mg \)
Explanation: The gravitational force \( F_g \) acting on an object with mass \( m \) is the product of the object's mass and the acceleration due to gravity \( g \), usually approximated as 9.8 m/s² on Earth.
4. Acceleration on Frictionless Surfaces
Formula: \( a = \frac{F_{\text{net}}}{m} \)
Explanation: On a frictionless surface, the acceleration \( a \) of an object is calculated by dividing the net force \( F_{\text{net}} \) by the object's mass \( m \).
5. Momentum and Impulse
Formula: \( \Delta p = F \Delta t \)
Explanation: The change in momentum \( \Delta p \) of an object is equal to the applied force \( F \) multiplied by the time duration \( \Delta t \) over which the force is applied. This concept is often used in collision and impact problems.
6. Circular Motion (Centripetal Force)
Formula: \( F_c = \frac{mv^2}{r} \)
Explanation: The centripetal force \( F_c \) required to keep an object of mass \( m \) moving in a circular path of radius \( r \) at speed \( v \) is given by this formula. This force acts toward the center of the circular path.
