BackPhysics Exam Study Guide: Forces, Work, Energy, and Motion
Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Exam Instructions and Calculator Settings
General Guidelines
This section outlines the rules and expectations for the exam, emphasizing academic honesty and proper problem-solving techniques.
Show all work: Full solutions, including equations and reasoning, are required for credit.
Units: All answers must include correct units.
Calculator mode: Ensure trigonometric functions are set correctly, e.g., , .
Ask for clarification: If a question is unclear, seek help during the exam.
Forces and Free-Body Diagrams
Analyzing Forces on Objects
Understanding how to draw and analyze free-body diagrams is essential for solving problems involving forces.
Free-body diagram: A graphical representation showing all forces acting on an object.
Types of forces: Tension, gravity (weight), normal force, friction, applied force.
Newton's Second Law:
Components of forces: Forces can be resolved into x and y components using trigonometry.
Example: For a ball of mass 0.4 kg moving in a horizontal plane at 0.7 m/s, the tension in the string provides the centripetal force required for circular motion.
Centripetal force:
Tension components: ,
Work, Energy, and Power
Work Done by Forces
Work is the transfer of energy via a force acting over a distance. The work done by different forces can be calculated using their respective formulas.
Work by a constant force:
Gravitational work:
Work-energy theorem:
Example: Calculating the work done by the gravitational force on a block sliding down an incline.
Power
Power is the rate at which work is done or energy is transferred.
Definition:
Application: Engine power required to accelerate a car.
Friction and Inclined Planes
Static and Kinetic Friction
Frictional forces oppose the motion of objects and are classified as static (preventing motion) or kinetic (opposing ongoing motion).
Static friction:
Kinetic friction:
Normal force: The perpendicular contact force exerted by a surface.
Example: Calculating the frictional force and normal force for a block on an inclined plane.
Spring Force and Hooke's Law
Elastic Potential Energy
Springs store energy when compressed or stretched, described by Hooke's Law and elastic potential energy.
Hooke's Law:
Elastic potential energy:
Work done by spring:
Example: A block attached to a spring is pulled and released; calculate its speed using energy conservation.
Impulse and Momentum
Collisions and Conservation of Momentum
Momentum is conserved in isolated systems. Impulse is the change in momentum resulting from a force applied over time.
Momentum:
Impulse:
Conservation of momentum:
Example: A ball collides with the ground and bounces back; calculate the impulse and final velocity.
Summary Table: Forces on an Inclined Plane
This table summarizes the main forces acting on a block on an inclined plane and their formulas.
Force | Formula | Direction |
|---|---|---|
Weight (Gravity) | Downward | |
Normal Force | Perpendicular to surface | |
Friction (Kinetic) | Opposite to motion | |
Applied Force | Parallel to surface |
Additional info:
Some diagrams and equations were inferred from context and standard physics curriculum.
All equations are provided in LaTeX format for clarity.
Examples and applications are based on typical introductory physics problems.