Topic 1 - Motion and Forces

• What is a scalar quantity?

  A scalar quantity is a physical quantity that has magnitude but no direction.
• What is a vector quantity?

  A quantity that has both magnitude and direction.
• What is the difference between a scalar and vector quantity?

  Scalar: A quantity that has only magnitude. Vector: A quantity that has both magnitude and direction.
• Distance is scalar, Displacement is vector
• Speed is scalar, Velocity is Vector.
• What is velocity?

  velocity is speed in a stated direction
• What is the formula for speed?

  Speed = Distance / Time

  
• What is a Distance/Time graph?

  A graph that shows the relationship between distance traveled and time elapsed. (look at the image).

  
• What is acceleration?

  Acceleration is the rate at which an object's velocity changes over time.
• What is the formula for acceleration?

  The formula for acceleration is a = (v - u) / t, where a is acceleration, v is final velocity, u is initial velocity, and t is time.

  
• What is the formula for uniform acceleration?

  $v^2-u^2 =$$2 *$$a *$$x$ "a" is acceleration and "x" is distance.
• what is a velocity/time graph?


  A graph that shows the change in velocity over time. The gradient is the acceleration.

  
• you can determine the speed of an object using lightgates.
• acceleration in free fall is 10 meters per second.
• What is Newton's first Law?

  A resultant force is required to change the motion of an object.
• Force is proportional to an object's acceleration but inversely proportional to an object's mass. F = m * a.
• What is weight?

  The force exerted on an object due to gravity. (Measured in Newtons).
• What is the formula for weight?

  Weight = mass x gravitational field strength.
• How do you investigate the motion of a trolley on a ramp?

  1. Gather equipment: trolley, unit masses, hanging hook, and a card for interrupting light gate beams.
  2. Set up the apparatus, including the ramp, and adjust its height until the trolley barely starts moving.
  3. Mark a consistent starting line on the ramp before the first light gate.
  4. Attach a hanging mass to the trolley, release it at the starting line, and let light gates record time and speed.
  5. Calculate acceleration using the formula: acceleration = change in speed / time.
• an object moving in a circular orbit at constant speed has a changing velocity.
• for motion in a circle, there must be a resultant force known as a centripetal force that acts towards the centre of the circle.
• What is inertia?

  The tendency for motion to remain unchanged.
• What is Newton's third law?

  When 2 forces collide with each other, they exert an equal and opposite reaction.
• What is momentum?

  p = mass * velocity.
• momentum 1 = momentum 2
• How do you work out force through momentum?

  $F =$$ΔMV/t$ force = final momentum - initial momentum/time.
• You can test a person's reaction time by using the ruler drop test. The longer the distance, the longer the reaction time.
• What is stopping distance?

  Thinking distance (when the driver identifies the threat) + braking distance (The distance it took for the car to become stationary).
• What are the factors that could affect the stopping distance?

  • Mass of the vehicle
  • Speed of the vehicle
  • Driver’s reaction time
  • State of the vehicle’s brakes
  • State of the road
  • Amount of friction between the tyre and the road surface
• the reaction time of the driver could be influenced by drugs or distractions.
• The braking distance would increase if the initial speed is high.
• What is the formula for a car's kinetic energy store?

  $1/2 *$$m *$$v^2 =$$F *$$d$ The kinetic energy stored in the car is equal to the work done by the brakes.