🎡AP Physics 1 AP Cram Sessions 2021

Key Concepts and Principles

• Newton's laws of motion describe the relationship between forces and motion
  • Newton's first law states an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force (inertia)
  • Newton's second law states the acceleration of an object depends directly upon the net force acting on the object, and inversely upon the mass of the object ($F=ma$)
  • Newton's third law states for every action, there is an equal and opposite reaction
• Work is done when a force that is applied to an object moves that object, expressed as the product of force and displacement ($W=Fd$)
• Energy is the capacity to do work and may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms
  • Kinetic energy is the energy of motion ($KE=\frac{1}{2}mv^2$)
  • Potential energy is stored energy of position ($PE=mgh$ for gravitational potential energy)
• Power is the rate at which work is done or energy is transferred ($P=\frac{W}{t}$)
• Momentum is the product of an object's mass and its velocity ($p=mv$)
  • The law of conservation of momentum states the total momentum of a closed system remains constant
• Impulse is the product of the net force on an object and the time interval during which it acts ($J=F\Delta t$)
• Torque is the rotational equivalent of linear force, causing an object to rotate about an axis ($\tau=rF\sin\theta$)

Fundamental Equations and Formulas

• Velocity: $v=\frac{\Delta x}{\Delta t}$
• Acceleration: $a=\frac{\Delta v}{\Delta t}$
• Force: $F=ma$
• Weight: $w=mg$
• Work: $W=Fd\cos\theta$
• Kinetic Energy: $KE=\frac{1}{2}mv^2$
• Gravitational Potential Energy: $PE=mgh$
• Power: $P=\frac{W}{t}$
• Momentum: $p=mv$
• Impulse: $J=F\Delta t$
• Torque: $\tau=rF\sin\theta$
• Period: $T=\frac{1}{f}$
• Spring Force: $F=-kx$
• Coulomb's Law: $F=k\frac{q_1q_2}{r^2}$

Problem-Solving Strategies

• Identify the given information and the quantity to be calculated
• Draw a diagram or sketch of the problem situation, labeling known and unknown quantities
• Determine which physics principles and equations are relevant to the problem
• Break down complex problems into smaller, more manageable steps
• Use dimensional analysis to ensure the units of the final answer are correct
• Substitute known values into the appropriate equations and solve for the unknown quantity
• Check the reasonableness of the answer by estimating or comparing to similar problems
• Analyze the result to see if it makes sense in the context of the problem

Common Misconceptions

• Confusing speed and velocity (velocity is speed with a specified direction)
• Believing that an object with a net force of zero must be at rest (it could be moving with constant velocity)
• Thinking that heavier objects fall faster than lighter objects (in the absence of air resistance, all objects fall with the same acceleration due to gravity)
• Assuming that an object's velocity must be in the same direction as the net force acting on it (the velocity and force can be in different directions)
• Believing that energy is "used up" or disappears (energy is conserved and can only be converted from one form to another)
• Thinking that an object with zero velocity must have zero acceleration (an object can have acceleration even if its velocity is momentarily zero, such as at the top of a tossed ball's trajectory)
• Confusing mass and weight (mass is an intrinsic property of an object, while weight is the force exerted on the object due to gravity)

Practice Problems and Solutions

1. A 2 kg object is pushed with a force of 10 N for 5 m. How much work is done on the object?

   • Given: $m=2\text{ kg}$, $F=10\text{ N}$, $d=5\text{ m}$
   • Work done: $W=Fd=(10\text{ N})(5\text{ m})=50\text{ J}$

2. An object is dropped from a height of 20 m. What is its velocity just before it hits the ground? (Ignore air resistance)

   • Given: $h=20\text{ m}$, $g=9.8\text{ m/s}^2$
   • Use the equation: $v=\sqrt{2gh}=\sqrt{2(9.8\text{ m/s}^2)(20\text{ m})}=19.8\text{ m/s}$

3. A 1000 kg car traveling at 30 m/s collides with a wall and comes to a stop in 0.5 s. What is the average force exerted on the car during the collision?

   • Given: $m=1000\text{ kg}$, $v_i=30\text{ m/s}$, $v_f=0\text{ m/s}$, $\Delta t=0.5\text{ s}$
   • Use the impulse-momentum theorem: $F\Delta t=m\Delta v$
   • Solve for force: $F=\frac{m\Delta v}{\Delta t}=\frac{(1000\text{ kg})(0-30\text{ m/s})}{0.5\text{ s}}=-60000\text{ N}$

Lab Experiments and Demonstrations

• Inclined plane experiment to demonstrate the relationship between force, work, and energy
  • Measure the force required to pull an object up an inclined plane at a constant speed
  • Calculate the work done and compare it to the change in potential energy
• Pendulum experiment to investigate the factors affecting the period of a pendulum
  • Vary the length of the pendulum and mass of the bob
  • Measure the period and compare it to the theoretical prediction ($T=2\pi\sqrt{\frac{L}{g}}$)
• Elastic and inelastic collision demonstrations using carts or balls
  • Observe the conservation of momentum in elastic collisions
  • Investigate the role of energy dissipation in inelastic collisions
• Hooke's law experiment using springs and weights
  • Measure the elongation of a spring for different applied forces
  • Plot the force-displacement graph and determine the spring constant

Exam Tips and Techniques

• Read each question carefully and identify the key information given
• Draw diagrams or sketches to visualize the problem situation
• Show all your work, including equations used and substitutions made
• Double-check your calculations and ensure the final answer has the correct units
• Manage your time effectively by skipping difficult questions and returning to them later
• Eliminate obviously incorrect answer choices in multiple-choice questions
• Justify your answers in free-response questions by providing clear explanations and reasoning
• Review your answers, if time permits, to catch any errors or omissions

Additional Resources and Study Materials

• Textbooks: "Physics" by Giancoli, "Fundamentals of Physics" by Halliday, Resnick, and Walker
• Online resources: Khan Academy, PhET simulations, AP Central (College Board)
• Study guides: "5 Steps to a 5: AP Physics 1" by Greg Jacobs, "Barron's AP Physics 1" by Kenneth Rideout and Jonathan Wolf
• Practice problems: "Schaum's Outline of College Physics" by Frederick J. Bueche and Eugene Hecht, "The Princeton Review: Cracking the AP Physics 1 Exam" by The Princeton Review
• Video lessons: Crash Course Physics, Bozeman Science, Flipping Physics
• Study groups and tutoring sessions with classmates or teachers
• Review sessions and practice exams offered by the school or local educational organizations
• Online forums and discussion boards for asking questions and collaborating with peers (AP Student Community, Reddit's r/APStudents)