# I have got a lab on 'Braking distance of a wooden block'?

• Bharat_prakash
In summary, the student was trying to figure out what to do next with their homework. They were having trouble with the graph and the gradient. They needed help to figure out what it meant.
Bharat_prakash

## Homework Statement

I have got a lab on 'braking distance of a wooden block' and I have to find an equation which fits our experiment and find the uncertainty. I have an equation but I can't find the uncertainty.

This is how, I went about my lab...

To find the relationship between the mass of the wooden block and the braking distance, we incrementally increase the mass of the wooden block. With the help of rubber bands, we project the wooden block in a linear motion on a plane surface. Then, we record the braking distance.

## Homework Equations

I have come up with these equations
lg⁡(d)=-0.8814 lg⁡(m)+3.9708

lg⁡(d)=-0.8814 lg⁡(m)+lg⁡(〖10〗^3.9708)

=lg⁡(m^(-0.8814) )+lg⁡(〖10〗^3.9708)

=lg⁡(m^(-0.8814) ) ×⁡(〖10〗^3.9708)

d=9350m^(-0.88)

=9350m^((-88)⁄100)

d^100=〖9350〗^100 m^(-0.88)

How do I find the uncertainity and how do I go about it? It would really helpful if you guys reply quickly, the lab is due tomorrow.

I assume you took multiple measurements to create that equation. The variability in those measurements should indicate the uncertainty.

Yes, I did take multiple measurements to create that equation. But what I don't get is, what will be my next step to find the uncertainty. I asked my teacher and he said, that the (max deviation - the average value) is my uncertainty but I really don't get what he means by that.

I also need to draw error bars on my graph and every point has a different uncertainty value but excel doesn't allow me to change the uncertainty value from point to point.

Thanks

Hey, I found out what to do with uncertainty although now I am on the graph part and I have to state what the gradient means.

I have plotted the graph of

On Y axis: Distance Travled by the wooden block
On X axis: Weight of the wooden block

I don't know what the gradient will mean or even if it means something? Thanks

If you've taken several measurements for each point, you can calculate the mean value (sometimes called just the average). For each of your measurements, then, you can calculate how far away from the mean value it is. Your teacher is suggesting that you use the largest value of this (ignoring minus signs) as a measure of spread.

It's not a good measure of spread, though. Imagine that you make a thousand measurements, and 999 of them are between 11 and 12, but you really mess up one measurement and get 18. Is 6-point-something really a fair measure of the spread? A better measure is the standard error on the mean - the standard deviation (look it up if you need to) of your measurements divided by the square root of the number of measurements.

You can do different errors for each point in Excel. One of the options let's you enter a cell range. Use that and enter the error bar values in the spreadsheet. For example, x-value in column A, y-value in column B, upper error limit in column C and lower error limit in column D.

## 1. What is the purpose of the lab on "Braking distance of a wooden block"?

The purpose of this lab is to study the relationship between the mass of a wooden block and its braking distance.

## 2. How is the braking distance of a wooden block measured?

The braking distance of a wooden block is measured by recording the distance it travels after being released from a certain height and then stopping due to friction.

## 3. What factors can affect the braking distance of a wooden block?

The factors that can affect the braking distance of a wooden block include the mass of the block, the surface it is sliding on, and the initial height it is released from.

## 4. How can the results of this lab be applied in real-life situations?

The results of this lab can help us understand the physics behind braking and stopping distances, which can be applied in real-life situations such as driving and designing braking systems for vehicles.

## 5. What safety precautions should be taken during this lab?

Safety precautions that should be taken during this lab include wearing protective gear such as goggles and lab coat, using proper techniques to handle the wooden block, and making sure the lab area is clear of any obstacles.

Replies
9
Views
2K
Replies
18
Views
2K
Replies
5
Views
2K
Replies
2
Views
511
Replies
13
Views
3K
Replies
4
Views
3K
Replies
13
Views
3K
Replies
9
Views
1K
Replies
7
Views
2K
Replies
20
Views
1K