P2.1 Motion

• Scalar

  a number that has only magnitude (size)
• Vector

  A number with magnitude and direction
• distance

  How far you travel in total
• Displacement

  how far you are from the start and in what direction
• Speed is a scalar
• Velocity is a vector
• $speed=$$\frac{dis\tan ce}{time}$
• $velocity=$$\ \frac{displacment\ }{time\ }$
• more mass, more momentum
• more velocity, more momentum
• Momentum measures how hard it is to stop an objects motion
• momentum= mass * velocity
• kgm/s = kg *m/s

  p = m * v
•  in a closed system, the total momentum remains constant, total momentum is always conserved
• conservation of momentum

  going right = pos

  going left = neg
• Stopping distance = thinking distance + Breaking distance
• Impact force = $\frac{momentum}{colision\ time}$
• acceleration is how quickly velocity changes
• acceleration = $\frac{change\ in\ velocity\ }{time\ taken}$
• $a\ =$$\ \frac{Δv}{t}$
• acceleration = m/$s^2$
• distance time graphs

  • steady line shows constant speed
  • flat line shows no movement
  • steeper line shows faster
• Displacement

  • steady line shows steady speed
  • flat line shows no movement
  • steeper means faster
  • line coming down shows returning to start
• the gradient tells us how fast an object is moving- velocity
• velocity time graphs

  • straight positive line shows constant acceleration
  • flat/horizontal line shows constant velocity , no acceleration
  • straight negative line shows constant deceleration
  • the steepness, the gradient shoes us the acceleration
• the area under the graph tells us the total distance travelled
• $v^{2\ }-u^2=$$2as$

  final velocity - initial velocity = 2 * acceleration* displacement
• final velocity - v - m/s

  initial velocity - u - m/s

  acceleration - a - m/$s^2$

  displacement - s - m

  time - t - s