(PP1) speed and height

• The main cause of error in this experiment is reaction time when the person starts and stops the stop clock
• Error due to reaction time

  kept to minimum:

  • repeating the timing for each height and calculating the average time
  • ensuring the time taken is as long as possible:
  • making the distance between A and B as long as possible;
  • keeping the vertical height as small as possible, so that the marble doesn’t move too fast.
• As the vertical height of the runway increases the average speed of the marble also increases
• we can say that the vertical height is not directly proportional the average speed as the line of best fit is not a straight line through the origin
• Calculate the average speed using the equation: average speed = Distance traveled / average time taken
• independent variable is the height of the runway
• dependent variable is the average speed of the marble. To calculate the average speed, we have to measure the time taken for the marble to travel a measured length of the runway.
• control variables are: the distance marble travels along the runway, the mass of the marble, the type of marble used, the surface of the runway, the initial speed of the marble.
• prediction - as the height of the runway increases, the average speed of the marble will also increase.
• As the height increases the gravitational potential energy of the marble will also increase.

  As the marble moves down, its gravitational potential energy is converted to kinetic energy.

  From the conservation of energy, the greater the amount of gravitational potential energy at the top, the greater the amount of kinetic energy at the bottom.

  If the marble has more kinetic energy at the bottom, it will have greater speed.