The experiment can be used to determine the acceleration due to gravity accurately when the slope of the ramp is extrapolated to 90 degrees.
Experimentally, the acceleration due to gravity is valid because when the ramp is set to a 90 degree angle, it essentially has no slope, so objects that are set at a 90 degree angle experience free-fall which is 9.8 m/s2. Using this knowledge, during the experiment if the ramp is set at a higher slope, it is essentially approaching the 90 degree angle. As it approaches the 90 degree angle, the cart on the ramp will be experiencing free-fall if the ramp was set at 90 degrees. So, the experiment can be valid because as the ramp increases in height the acceleration due to gravity increases since the cart will be moving faster. Since the cart is moving faster as the slope of the ramp increases it approaches free-fall. If the ramp was set to a lower slope, the cart would then move slower but the acceleration due to gravity would still affect it. It would affect it because then the cart would experience a slower acceleration as the gravity is lower.
In the experiment there were many possibilities for error. In the experiment, the slope of the ramp was set at 6 books. Taking this, we divided 100 by 6 then multiplied it by the average slope which was .78456. The answer which was obtained was 13.07 m/s2 which was clearly not in agreement with the accepted value of free-fall. This answer does not make much sense in context of the problem because if the slope of the ramp was lower, then it should have been less than the accepted value of free-fall. Knowing this, we know that there were possible errors regarding the slope or height of the experiment. But, the acceleration due to gravity can be accurately portrayed experimentally at 90 degrees.