forces

• Newton’s first law: a resultant force is required to change the motion of an object. if all the forces on an object are balanced it either remains at rest or continues in a straight line at constant speed
• Newton’s second law: non-zero resultant force acts on an object, then it will cause the object to accelerate
• Newton’s third law: when 2 objects interact, the forces they exert on each other are equal and opposite
• Acceleration = rate of change of velocity, unit: m/s2
• Scalars only have size (magnitude)
• Mass, time, distance, speed, temperature are all scalars
• Vectors have both size and direction (vectors can be negative)
• Displacement, velocity, acceleration, momentum Momentum = mass in motion, mass + velocity are all vectors
• Speed = distance/time, v = d/t
• Acceleration [ change in velocity ] = ( final velocity/initial velocity ) / time, a = (v-u) / t
• In an electrical field, a non-contact force occurs in a charge

  In a gravitational field, a non-contact force occurs on a mass
• Everything on earth when dropped will increase at a rate of 10m/s every second that its falling
• how to improve accuracy: more precise equipments, calculate an average, plotting results on graph with line of best fit, eliminating errors and anomalies
• The area under a velocity-time graph represents the displacement (or distance travelled) by an object
• Acceleration happens because of an unbalanced force
• Force = mass x acceleration, f=ma
• Weight = mass x acceleration of gravity, W = mg
• v2 = u2 + 2as (constant acceleration only)

  v = final speed, u = initial speed, a = acceleration, s = distance travelled
• Terminal velocity = the maximum velocity/speed

  1. Accelerates downwards because of gravity
  2. As the speed increases, air resistance also increases
  3. At terminal velocity, the weight of the object due to gravity is balanced by air resistance so the resultant force is 0

  leads to CONSTANT ACCELERATION
• Distance = 1/2at2 (t= reaction time)

  KE = 1/2 m v2 ,
• moments are a turning force around a fixed pivot

  Force x perpendicular distance to the pivot
• m = fd, moment of a force = force × distance
• weight of a body acts through its centre of gravity/mass
• Hookes law: force is proportional to extension

  Force = spring constant x extension, F = kx
• elastic deformation: does return to its original shape after the forces have been removed

  inelastic deformation: does not return to its original shape after the forces have been removed
• Limit of proportionality: the amount of force that leads to object to not be able to return to its original shape when the force is removed