Motion and forces: scalars,vectors,graphs,acceleration

• if the velocity of an object changes, it must be accelerating.
• IThe bigger a mass, the greater its gravitational field strength.
• Mass doesn't change
• The greater the force, the bigger the acceleration or deceleration.
• The greater the mass of the object, the smaller the acceleration or deceleration.
• What is inertia

  Objects with mass have a tendency to stay at rest or in the same state of motion.
• Inertial mass is a measure of how hard it is to change the velocity of an object. Calculated by force ÷ acceleration
• Examples of vectors:

  displacement, velocity, momentum, acceleration, and all forces (e.g. weight, friction).
• Displacement is how far an object moves measured from start to finish in a straight line. In other words, displacement shows the overall change in position of an object.
• Examples of scalars are:

  distance, speed, energy and mass.
• Vector quantities have magnitude(size) and direction, while scalar quantities have magnitude only.
• Distance(squalar quantity) is how far an object moves
• Displacement(vector quantity) is how far an object moves measured from start to finish in a straight line
• Velocity is speed of object in particular direction

  
• Distance time graph

  • Constant speed shown as straight diagonal line
  • Stationary speed is show as flat line
• On distance time graph, the steeper the gradient of line, the higher the speed
• To calculate the speed on distance time graph find the gradient
• Distance and time can be measured in lab

  • Tape measure or ruler used to measure distance
  • Stopwatch or light gate used to measure time
• When velocity of object is increasing(speeding up) its accelerating
• An object traveling at constant velocity is not accelerating
• Acceleration(m/s^2)= change in velocity(m/s) / time(s)
• Uniform acceleration means the amount of acceleration doesn't change
• Uniform acceleration = (fianl velocity)^2 - (initial velocity^2) = 2 × acceleration × distance
• Near to earth's surface an object falling freely has acceleration 10 m/s^2
• Object falling has downward force(weight) which makes object accelerate downwars
• To calculate displacement calculate area under velocity time graph
• Velocity time graph

  • Straight line means constant velocity
  • Diagonal line means accelerating/ decelerating
• What makes object accelerate downwards?

  Object falling has downward force(weight)