7 - Acceleration

• Investigating the acceleration of an object:

  1. Set up the apparatus
  2. Hold the toy car at the starting point and let go
  3. Record the time that the car passes each distance marker, even recording a video of it to be able to play it back several times for more accurate results
  4. Repeat the experiment several times, decreasing the mass on the end of the string each time e.g. 80, 60, 40, 20g so the weight decreases each time
• The apparatus includes a toy car attached to a string looped around a pulley with the other end of the string attached to a 100g mass. We also have a timer, and chalk lines at equal intervals every 10cm across the string

  A) toy car

  B) string

  C) pulley

  D) chalk lines

  E) timer

  F) 100g mass

  
• In this experiment, the mass of the object (toy car + string + mass) must be kept constant, therefore if some of the mass from the end of the string was taken away then it must be transferred onto the toy car so the overall mass of the object remains constant
• Newton's second law of motion tell us that the acceleration of an object is proportional to the force applied. The force in this case is the weight of the mass on the end of the string. We should find that the acceleration of the toy car is proportional to the mass on the other end of the string
• We can use the same experiment to investigate how varying the mass of the object affects the acceleration produced by a constant force. To do this, the mass on the end of the string is kept constant (100g), however we now attach a mass to the toy car e.g. 200g and repeat the experiment, increasing the mass attached to the toy car each time
• Newton's second law also tell us that the acceleration of an object is inversely proportional to the mass of the object. Therefore, with the experiment investigating the change of mass, we should find that as we increase the mass of the toy car, the acceleration decreases.