Lab 3 Quiz

1) For this equation distance moved is equal to displacement, therefore velocity is equal to time. Thus, distance/time=speed. Or, Length of ball divided by the time the light is blocked is speed.
2)For this, set up a triangle with y displacement as y axis and x velocity as x axis. Find velocity in the Y direction using DeltaVy^2=2gDeltaY and then use DeltaVy=gt to solve for time. Then plug t into displacement of x equation.
3)Set equation equal to g. Find relative error of slope (s). Propogate error using formula (DeltaS/S)^2=|n|RelativeError. Multiply by 100 for percent error.

for 2 by displacement of x equation i mean DeltaX=Vx0*t

Question 2: This is my calculations... can someone tell me where I went wrong?
t=sqrt((2*(y-y0))/g) = sqrt((2*-1.392)/-9.81)=.5327s
x= x0 + Vx0*t -->x= 0+ 1.392*.5327
x= .741m
It then asks if it should be either negative or positive depending on whether you used one or two eqns. I put negative for 2 eqns. Any insight??

Question 3: What is this question. I was able to solve for g, but I don't know what values to plug in. The only other numbers are height and the slope and its error, but how is that related to the Vx and the x?

Please help!! I have lab tonight at 8!!! EKKK! Thanks!!!

I used:

ΔV_y² = 2*g*Δy

Solve for ΔV_y². You can really just plug in the right side, then square it.

Now we have to find t

ΔV_y = g*t => t = ΔV_y/g

We finally have to find Δx, so we again just plug in.

Δx = V_x0*t

You are given the Δy, which is in cm, convert it to meters.
You are also given a velocity of the horizontal component, V_x0 in m/s, so there is no conversion there.

I still don't understand what to do with question 1, I keep getting it wrong. I put the distance into meters and time into seconds and did m/s but the answer keeps coming out wrong. Am I not supposed to convert? Or is there a negative ?

Try with a negative

Please help me guys with Q#3, I completely dont know how to do it.

Take the relative error. Multiply by 2. And than multiply by 100. To get the relative error just take the numbers they gave you in the (...) and divide them with the smaller number(which is given with a +- sign)on top and the bigger number on the bottom.