BRAINCAKE

Motion and forces

Edexcel GCSE PhysicsTopic 2 of 1533 lessons

Revision notes for Motion and forces in Edexcel Physics (1PH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Scalar quantitiesA scalar quantity has magnitude, which means size, but no specific direction.
  2. Vector quantitiesA vector quantity has both magnitude and a specific direction.
  3. Vectors compared with scalarsThe difference between scalar and vector quantities is direction.
  4. Examples of vectors and scalarsYou need to recall which quantities are vectors and which are scalars.
  5. Velocity and speedSpeed tells you how fast something moves, and it has magnitude only, so it is a scalar.
  6. Speed, distance and timeFor a moving object, (average) speed = distance ÷ time.
  7. Distance/time graphs and speedA distance/time graph shows how far an object is from its starting point as time passes.
  8. Calculating accelerationAcceleration is how quickly velocity changes.
  9. The equation v² − u² = 2axWhen an object moves with constant (uniform) acceleration, its velocities, acceleration and distance are linked by one equation: (final velocity)2 −…
  10. Velocity/time graphs and accelerationA velocity/time graph shows how the velocity of an object changes with time.
  11. Measuring speed in the laboratorySpeed = distance ÷ time, so to find the speed of an object you must measure a distance and a time.
  12. Typical speedsYou should know the size of some everyday speeds, in metres per second.
  13. Acceleration in free fall and everyday accelerationsAn object is in free fall when the only force acting on it is gravity.
  14. Newton's first lawNewton's first law says that a body stays at rest, or keeps moving at a constant velocity, unless a resultant force acts on it.
  15. Newton's second lawNewton's second law links the resultant force on a body to its acceleration.
  16. Weight and gravitational field strengthWeight is the force acting on a mass because of gravity.
  17. Measuring weightWeight is a force, so it is measured in newtons using a newtonmeter, also called a spring balance.
  18. Weight and gravitational field strengthGravitational field strength, g, is the force on each kilogram of mass.
  19. Core Practical: Force, mass and accelerationThis core practical tests Newton's second law, F = ma.
  20. Circular motion and changing velocitySpeed tells you how fast an object is moving.
  21. Centripetal forceBy Newton's first law, an object keeps moving in a straight line at constant speed unless a resultant force acts on it.
  22. Inertial massEvery object resists changes to its motion.
  23. Newton's third law and collisionsNewton's third law says that when object A exerts a force on object B, object B exerts a force on A that is equal in size and opposite in direction.
  24. MomentumMomentum is a property of any moving object.
  25. Momentum in collisionsMomentum is mass multiplied by velocity, so it has a direction.
  26. Force and change in momentumNewton's second law can be written in terms of momentum.
  27. Measuring reaction timesReaction time is the time between a stimulus (something you see or hear) and your response.
  28. Stopping distanceWhen a driver sees a hazard and stops the vehicle, the total distance travelled is the stopping distance.
  29. Factors affecting stopping distanceStopping distance depends on several factors, and each one affects the thinking distance, the braking distance, or both.
  30. Factors affecting reaction timeA driver's reaction time is not fixed.
  31. Dangers of large decelerations and estimating forces on the roadA deceleration is an acceleration that slows an object down.
  32. Estimating stopping distances at typical speedsWhen a driver sees a hazard, the car does not stop at once.
  33. Work done and braking distanceWhen a car brakes to rest, the brakes exert a force over the braking distance.

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