motion and forces

• vector quantities have a magnitude and specific direction
• scalar quantities have magnitude but no direction
• vector quantities include: force, velocity, displacement, weight, acceleration, momentum ect
• scalar quantities include: speed, distance, energy, mass, temperature, time ect
• velocity is a vector but speed is a scalar quantity
• distance is how far an object has moved, its a scalar quantity, so it has no direction
• displacement is the shortest distance between two points on a straight line, it's a vector because it has both magnitude and direction
• velocity is the rate at which something changes position, its a vector quantity as it has both magnitude and direction
• speed is the rate at which something moves, its a scalar quantity as it doesn't have any direction
• speed shows distance travelled in a certain time
• distance travelled(m)=average speed (m/s)x time (s)

  
• speed(m/s)=distance(m) / time(s)
• walking speed: 1.4 m/s (5km/h)

  running: 3 m/s (11km/h)

  cycling: 5.5 m/s (20km/h)
• cars in a built up area: 13 m/s(47km/h)

  cars on motorway: 31m/s(112km/h)

  aeroplanes: 250m/s(900km/h)

  trains: up to 55m/s(200km/h)

  ferries: 15m/s(54km/h)
• wind speed: 5-20m/s

  speed of sound in air: 340m/s
• light gates are used to measure short time intervals. they get rid of human error due to reaction times
• walking speed is measured by a rolling tape measure, and markers for distances
• you can also use a video to measure speed, to see how far the object moves per frame
• acceleration is how quickly youre speeding up
• acceleration is the change in velocity in a certain amount of time
• a= (v-u) /t
• v2 - u2 = 2 x a x x
• acceleration (g) in free fall is 10m/s2
• newtons first law= resultant force is needed to make something start moving, speed up, or slow down
• if the resultant force on a stationary object is zero, the object will remain stationary. if the force on a moving object is zero, itll carry on moving at the same velocity
• F = m x a
• W = m x g
• a non zero resultant force will always produce acceleration/deacceleration in the direction of the force
• weight is a scalar quantity
• weight is measured in kilograms with a mass balance
• weight is the force acting on an object due to gravity
• mass is the amount of 'stuff' in an object
• gravity is caused by the gravitational field around earth
• weight is a force measured in newtons, the forcce is acting from a single point called centre of mass
• weight is measured using a calibrated spring balance (newton meter)