What would affect gravity during this experiment?

In summary: If you got results like 9.815, 9.816, 9.818, 9.819 then your answer would be something like 9.815 +/- 0.001.
  • #1
exparrot
21
0
I did a Newton's 2nd Law experiment for my physics lab. One of the write-up questions asks to identify at least 2 causes why your calculated value of g is not equal to 9.8 m/s2. It also asks to explain how would each cause affect your data and what would make the experimental value bigger or smaller.

So in the experiment, we had set up an air track with a pulley attached to the end of the track. A cart rested on the airtrack, a string was tied to one end of the cart, over the pulley to a 5 gm weighted hanger. To keep the mass constant, 110 gram weights were placed on the cart, and after each run, the weights were transferred to the hanger. Five trials were done.

Calculations from my data gave an acceleration of 9.81540 m/s2 and against the actual value of g, I get a percent error of 0.0550 %. However since I'm suppose to consider why I would not get the same value for acceleration due to gravity, would that be because of some other force, such as tension (which I don't imagine would interfere) or the normal force? I'd appreciate if anyone has some idea(s) and could help me out with this. Thanks!
 
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  • #2
You don't say exactly what you determined with your setup, but I assume it was the acceleration of the cart and from this you got g. I will list some assumptions you probably made, but you have to figure out if they would make any difference to your value of g and in what direction.

1. The pulley is massless.
2. There is no friction on the track or the pulley.
3. There is no air resistance.
4. The track is exactly horizontal.
5. The string is massless.
 
  • #3
Another point, 9.81540 m/s2 is suspicously accurate - at that level you can't even know the local value of 'g' without doing a geological survey.

Presumably you did the experiment more than once?
Look at the range of the answers.
If you actually got results like, 9.81, 9.80, 9.82, 9.81 for example then your answer would be something like 9.81 +/- 0.1
 

1. What is the relationship between mass and gravity?

According to Newton's Law of Universal Gravitation, the force of gravity is directly proportional to the mass of the objects and inversely proportional to the square of the distance between them. This means that as the mass of an object increases, its gravitational pull also increases.

2. Does the height at which the experiment is conducted affect gravity?

Yes, the height at which an experiment is conducted can affect gravity. This is because the force of gravity is weaker at higher altitudes due to the larger distance between the objects and the Earth's center of mass. However, for most experiments, the difference in gravity at different heights is negligible.

3. How does the shape of an object affect gravity?

The shape of an object does not directly affect gravity. However, the mass and distribution of that mass within the object can impact the gravitational force it exerts. For example, a larger and denser object will have a stronger gravitational pull than a smaller and less dense object.

4. Will the presence of other objects near the experiment affect gravity?

Yes, the presence of other objects near the experiment can affect gravity. This is because objects with mass exert a gravitational force on each other. However, the effect of other objects on the experiment's gravity may be minimal depending on their distance and mass.

5. Can the speed of an object affect gravity?

No, the speed of an object does not affect gravity. The force of gravity is determined by the mass and distance between objects, not their speed. However, the speed of an object can affect its motion due to the force of gravity, such as in the case of orbiting objects.

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