The Acceleration Due to Gravity, the "g Lab"
As we have seen in class when an object is dropped from rest the object experiences a constant acceleration. This means that the objects speed increases at a constant rate. The rate of the velocity increase is called the acceleration due to gravity and is denoted by the small letter g. The value for g is approximately equal to 10 meters per second per second, or 10 m/s squared. As we also have seen Galileo determined that the distance an object travels with time as it is dropped and experiences free fall is:
distance traveled = 1/2 * g * time squared
d = 1/2 * g * (t squared)
We can use this second equation to measure what the acceleration of gravity is and we should get around 10 m/s squared.
Today's lab will be on measuring g. Using the second equation we can rearrange it by using Algebra so that we get the equation:
g = (2 * d)/(t squared)
This is how you and your group is going to measure g. You will drop an object from some height and measure that height and the time it takes to drop to the ground and this is how you will get g.
Part 1: Select a point to drop your object from (starting at rest) and measure the distance from that point to the ground. This is the distance d in the above equation. Show your data.
Part 2: Drop your object from this height for five different trials. Remember to drop it from the same height each time. Write down the time for each of the five trials. Then calculate the average time for these five trials (add the five times up and then divide by 5). Write down the average time.
Part 3: Using the distance that you measured for the object to drop and the average time it took to drop that distance calculate the value for g that you just measured by using the equation: g = (2 * d)/(average time squared). Write down your result. How does this compare to the accepted value of 9.8 meters per second squared? Why might your result be different from the accepted value?