I\'m writing report about free falling in physics class with picket fence, Photo
ID: 1705286 • Letter: I
Question
I'm writing report about free falling in physics class with picket fence, Photogate and Logger pro.First time, I measured the picket fence pattern interval . I got 5.01 cm(old width) of width of the fence. And I changed the width to 4.482cm(new width).
so, according to old width, I got acceleration=9.803, initial velocity = 0.206
on new width, I got acceleration=4.482, initial velocity=0.261
so, here is questions.
1)what has happened here? In other words, exlpain the difference in the numbers you obtained for the two runs between new width and old width.
2) How Photogate and ULI are configured to measure time?
3) How does the software compute the velocity?
4) How will the computed velocity be affected by the new width?
5) How will the computed acceleration be affected by the new width?
6) How does this compare to what actually happened?
7) Finally, here is a physical reasoning question. You release the fence from rest; why is there an initial velocity in all of your runs?
8) Are the values for the initial velocity magnitudes reasonable if your explanation is correct? Make an estimate of these magnitudes as part of your answers.
Explanation / Answer
"Falls freely" means "has a constant acceleration due to gravity,"so we can use the constant-acceleration equations to determine our target variables. We take the origin O at the starting point,the coordinate axis as vertical,and the upward direction as positive.Because the coordinate axis is vertical,let's call the coordinate y instead of x.We replace all the x's in the constant-acceleration equations by y's.The initial coordinate yo and the initial velocity voy are both zero.The acceleration is downward (in the negative y-direction),so ay = -g = -9.8 m/s^2.Hence our target variables are the values of y and vy at the given times. At an arbitrary time,the position and velocity are y = voy * t + (1/2)ay * t^2 and vy = voy + ay * t