lmrp

• vector quantities have magnitude and direction e.g force , velocity , displacement
• scaler quantities have magnitude and no direction e.g speed , distance , mass , temperature , time
• A force is a push or pull on an object caused by it interacting with something
• contact force - force that is exerted between two objects that are in contact with each other e.g friction ,normal contact force , tension
• Noncontact force is a force that does not involve physical contact between two objects. e.g electrostatic ,gravitation or magnetic force
• Mass is the amount of matter in an object and it is the same everywhere
• weight is the force of gravity acting on an object
• resultant force is the sum of the forces acting on an object. it is a single force that represents all forces
• an object has been elastically deformed if it can go back to its original shape and length after the force has been removed
• objects that can be elastically deformed are called elastic objects
• an object is inelastically deformed if it will not return to its original shape and length after the force has been removed
• the stiffer the spring the greater the spring constant
• investigating the link between force and extension

  • measure the natural length of a spring with a ruler clamped to the stand, take readings at eye level, and add a marker to the bottom of the spring to make readings more accurate
  • add a mass to the spring and allow it to come to rest, record the mass and measure the new length, the extension is the change in length
  • repeat the experiment
  • plot a force-extension graph
• Moment is the turning effect of a force
• to get maximum moment , push at right angles to the spanner
• density is the measure of compactness of a substance
• upthrust is equals to the weight of the fluid displaced by the object
• if the upthrust is equals to the objects weight , the forces balance and the object floats
• if an objects weight is more than the upthrust , the object sinks
• as altitude increases atmospheric pressure decreases
• acceleration is change in velocity with time
• distance time graph 


  • straight uphill section represents steady speed
  • flat section represents stopping
  • curves represent acceleration and deceleration
• Velocity time graph


  • uphill section represents constant acceleration
  • flat section represents steady speed
  • downhill section represents deceleration
  • curve represents changing acceleration
• drag is resistance in a fluid -air resistance is a type of drag
• to reduce drag keep the object streamlined
• terminal velocity in fluids

  • when an object first sets off the force of gravity is much more than the frictional force slowing it down so it accelerates
  • as speed increases , friction builds up and this reduces the acceleration until eventually frictional force is equals to accelerating force i.e resultant force = zero here it has reches maximum sppeed or terminal velocity
• newtons first law states that an object will remain at rest or in motion unless acted upon by a resultant force
• newtons second law of motion states that acceleration is proportional to resultant force
• newtons third law of motion states that for every action there is an equal and opposite reaction
• inertia is the tendency for motion to remain unchanged
• Investigating how mass and force affect acceleration

  1. Set up the trolley so it holds a piece of card with a gap in the middle that will interrupt the signal on the light gate twice

  2. Measure the length of each card and input it to the software

  3. It would measure the velocity for each card
• investigating how mass and force affect acceleration

  
  

  4. Connect the trolley to a string which goes over a pulley and is connected to a hook on the other side

  5. The hook and masses attached provide an accelerating force

  6. Mark a starting line on the table the trolley is on, so the trolley would travel same distance to get to the light gate

  7. Place the trolley on the starting line, hold it then release it

  8. Record the acceleration measured by the light gate, this is the acceleration of the whole system

  9. Repeat it twice to get an average acceleration
• to investigate effect of mass

  • add masses one at a time to the trolley to increase mass
• to investigate force


  • keep the mass on the trolley the same but change the mass of the the hook
  • to do thus start with all the masses on the trolley and transfer one at a time to the hook
• stopping distance = thinking distance + braking distance
• thinking distance is how far the car travels during the driver's reaction time
• braking distance is the distance taken to stop under the braking force
• factors affecting thinking distance

  • speed - the faster you are going the further you will travel during the time you take to react
  • reaction time - the longer your reaction time , the longer your thinking distance
• factors affecting braking distance

  • speed
  • weather or road surface
  • condition of your tyres
  • condition of your brakes
• reaction time


  • sit with your arm resting on the edge of a table
  • get someone else to hold a ruler so it hangs between our thumb and forefinger , lined up with zero
  • without giving any warning , the person holding the ruler should drop it . close your thumb and finger to catch the ruler as fast a s possible
  • the longer the distance , the longer the reaction time
  • repeat the experiment with the same person and same ruler