Paper one

• in distance time graphs the gradient the (slope) at any point can be used to calculate an objects speed and when the slope is curved you draw a tangent at that point to calculate its speed .
• newtons first law teaches that unless acted upon by a force the motion of an object will remain stationary or in motion
• newtons second law teaches acceleration is directly proportional to the resultant force acting upon an object , the larger an objects resultant force the larger its acceleration
• mass is a scalar quantity and measured in kilograms whereas weight is a vector an is the amount of force an object experiences due to gravity shown in the equation weight = mass x gravity (10N)
• circular motion - if an object is travelling in a circle at a constant speed it is constantly changing it velocity so its also constantly accelerating because of this there must be a resultant force acting upon it , this force also acts towards the centre of the circle these opposing forces result in centripetal force
• predict what would happen if we reduced the mass of the trolley - the less massive the trolley the smaller the gravitational potential energy and the smaller the increase in kinetic energy so the slower the trolley travels
• theory : the greater the angle of incline the faster the trolley will travel down the ramp as the angle increases the gravitational potential energy decreases more quickly resulting in a higher kinetic energy which results in a faster speed
• Investigating motion - trolley

  1. Measure the trolleys mass and the hanging masses

  2. Adjust the height of the ramp until the trolley begins to move

  3. Mark a line just before the first light gate so that the trolley travels the same distance each time

  4. The first light gate records the initial speed of the object

  5. Attach a hanging mass and let go at the starting line

  6. Each light gate records the time at which the trolley passes through
• Acceleration

  Change in speed / time
• Calculating acceleration

  1. Initial speed in light gate one

  2. Final speed in light gate one

  3. Time it takes to travel between the two
• Altering height


  Changes the forces eg the force due to gravity
• Acceleration

  • Depends on the mass of the trolley and the size of the accelerating force
  • Force and acceleration are proportional (F=ma)
• A heavier trolley means a slower acceleration
• Inertia is an object maintaining the same motion until acted on by a resultant force an objects inertial mass is how hard it is to change it’s velocity and is found using m = f / a
• Newtons third laws says when two objects interact the forces they exert on each other are equal and opposite
• in closed systems the total momentum before is the same after an event this is the conservation of momentum
• Stopping distance = thinking distance + braking distance
• Thinking distance is the time taken for a driver to react to a hazard and applying the brakes and is determined by

  • a persons reaction time , this is increased by tiredness alcohol drugs and distractions
  • a persons speed the faster your moving the the more you travel in your reaction time
• Braking distance is how far the car travels once brakes are applied and affected by

  • the speed the faster the car the more kinetic energy
  • the mass the more mass the more force it will take to slow down
  • brake conditions worn or faulty brakes won’t brake with as much force
  • friction between your tires and the road
• Efficiency = useful energy transferred / total energy give.
• Lubrication reduces energy transferred by friction and reduces thermal energy radiated into the surroundings

  insulation reduces the rate of energy transfers by heating via conduction houses have cavity gaps to reduced energy transferred via conduction as air has a very low thermal conductivity
• waves transfer energy and some transfer information

  • transverse have particles that travel perpendicular to the direction of the wave
  • longitudinal waves travel have particles that vibrate parallel to the waves direction
• Waves behave three ways at boundaries

  • absorbed transferring energy to the materials energy stores
  • transmitted the waves carry on travelling through the new material and usually refracted
  • reflected it is sent back away from the new material this is how echoes ocurr
• When a wave refracts its wavelength changes when it experiences a change of density if a wave travel alongs the normal it changes speed and not refracted

  the wave bends towards the normal it slows down

  the wave bends away the normal it speeds up
• the angle of incidence is between the incoming light ray and the normal line , the angle of refraction is the angle between the normal line and the outgoing light ray
• Alpha decay decreases the charge and mass of the nucleus - two protons and two newtrons are emitted

  • a helium nucleus
• Beta minus decay has a neutron become a proton and the atomic number increases as there is a new proton but the mass number doesnt as the neutron just becomes a proton

  • an electron is the only thing emitted
• Beta plus

  • a proton becomes a positron and is emitted decreasing atomic mass
  • the proton also becomes a neutron so the mass numbers stays the same
• Neutron emissions decreases the mass number by one as a neutrin is emitted
• Gamma radiation changes neither mass number or atomic as it only releases excess energy
• Background radiation is low level radiation around us all the time

  • exposure to radiation is called irradiation everyone is constantly irradiated by background radiation
  • if unwanted radioactive atoms get on an object it is contaminated , these atoms can decay releasing radiation which can cause mutated cells result in illnesses such as cancer
• Resultant force is the overall force on a point or object along any direction e.g right to left
• Interactions between objects cause forces for example friction is produced between a tyre and a road