Investigating Newton S Laws of Motion

Physics 2A/B 2011 Investigation 1: Investigating Newton’s Laws of Motion

Background: Sir Isaac Newton (1642-1727) was a philosopher/scientist who thought long and hard about what makes things move. Observations made by Newton led him to conclude that if a net force acted on an object then its speed would change. His second law of motion essentially states “When a net force acts on an object then it will accelerate. Its acceleration will be proportional to the net force acting and inversely proportional to the mass of the object”.

Your Investigation: Write an hypothesis relating acceleration and accelerating force that is consistent with Newton’s second law and conduct an investigation to test your hypothesis. Your experiment should be designed to provide data that tests the validity of your hypothesis. Hint: You should consider arranging your Equipment at your disposal: apparatus as shown here. The accelerating • dynamics trolley force is generated by the weights on the • mass balance hanger. Remember the whole mass of the • 50g slotted masses, around trolley and the masses on the hanger are all 2kg per group being accelerated by the accelerating force. • stopwatch

• bench top Extra masses on • metre rule trolley • graph paper • string • pulley

The Report: Your report will include the following:  The hypothesis you have written. This must be consistent with Newton’s 2nd Law.  A fully labeled 2D sketch of the apparatus you will use.  A very brief outline of what you will do.  Tabulated data with units and a reasonable number of significant figures. Include space for processed data.  A suitable graph relating to the variables in your hypothesis. The data will need to be processed so that the plotted data forms a straight line.  Write a brief conclusion to your research. You should refer to your graph to support your conclusion.  Describe in detail any two major sources of error in your experiment. You should identify these as being due to technique or equipment and estimate the % error they introduce to particular measurements.  Determine by calculation the value of the gradient of your straight line graph. Remember to include the units with your gradient.  What does the gradient represent? Is the value of your gradient consistent with your particular experiment? Explain.

Assessment: This will include a peer assessment of your report and a validation test.