Forces and Systems Lab- Relationship questions

[xkaibob]

I have a lab report due tomorrow on forces. Basically, we were supposed to calculate the kinetic friction of a "frictionless" system on a level place, an incline plane accelerating upwards, and an incline plane accelerating downwards.

I solved for mk by using the equation m(at + aA)= T-(mk)mg. I also calculated for tension and acceleration.

*Please note that the first m stands for mass of the sled, the (mk) means the kinetic frictional force, and the final m is the mass of the weight attatched.

This is my data thus far:

Experimental Results:

Level:
Acceleration: 4.89
Tension: .72
mk: .059

Downward Incline:
Acceleration: 6.642
Tension: .9798
mk: .087

Upward Incline:
Acceleration: 3.078
Tension: .454
mk: .039

Theoretical Results:

Level:
Acceleration: 4.038
Tension: .596
mk: .047

Downward Incline:
Acceleration: 5.885
Tension: .868
mk: .078

Upward Incline:
Acceleration: 3.478
Tension: .513
mk: .045


I've made the observation that the greater the acceleration, the greater the frictional force opposing the motion of the object.

Is that correct or am I missing something? And what am I supposed to incorporate the percent error of the frictional force for?

Thanks for any help. :]

 

[member 553083]

Yes, your observation is correct. The greater the acceleration, the greater the frictional force opposing the motion of the object. This is because the more force you apply to an object, the more friction it will experience. To incorporate the percent error of the frictional force, you can calculate it by taking the difference between the experimental and theoretical results and dividing it by the theoretical result. For example, for the level plane, you would take (.059 - .047) / .047 = 22.4%. This provides an indication of how accurate your results are compared to the expected values.