I have not done much physics before: I don't get how to do questions that deal with what happened in a particular SECOND
So questions like:
- A stone which is dropped from rest into a mine shaft falls a distance of 24.5 m DURING THE LAST SECOND. Find depth of the shaft
or
- Starting from rest a rocket accelerates at a rate of 4 m/s2. What distance will it travel DURING THE TENTH SECOND
I do not have enough experience with physics to understand these; although i think it can be determined
by just these equations:
a= v2-v1/t
v22 = v12 + 2ad
and
d = v1t + 1/2 at2
In both I guess v1=0, and the distance is given for the first, the acceleration for the second.
Do I also incorporate gravity(9.8 m/s2)? Please tell me how to approach these.
Thanks
find when the last second, on the second question, like at t=10 find the distance it has traveled. Then find the same distnace for t=9. The difference in distances is the distance in the last second.
There is another way (calculus differentials) way.
find ddistance/dt=vi+at at t=start of last second, then use this as the vi for the tenths second. d=vi+at where t is just one second.
I prefer the first way I illustrated.
thanks!
but what do i do when the time isnt given like in the first question?
wait.. i didn't get the right answer.
i got 530 m in the 10th second
and then 432.9 in the 9th
subtracted, they give 97.1 but the answer should be 38 m?
To solve these types of problems, you can use the equations of motion, also known as kinematic equations. However, the equations you provided are not sufficient to solve them accurately. Here's how you can approach these problems step by step:
1. Identify the information given: In the first problem, you are given that a stone falls a distance of 24.5 m during the last second. In the second problem, you are given that a rocket starts from rest and accelerates at a rate of 4 m/s^2.
2. Determine the variables and equations to use:
- For the first problem, you need to find the depth of the mine shaft. You know the distance (d) and the time (t), and you need to find the acceleration (a). The equation that relates these variables is d = (1/2)at^2.
- For the second problem, you need to find the distance traveled. You know the acceleration (a) and the time (t), while the initial velocity (v1) is given as zero. The equation that relates these variables is d = v1t + (1/2)at^2.
3. Solve the first problem:
- The stone is dropped from rest, so its initial velocity (v1) is zero.
- You are given the distance (d) as 24.5 m and the time (t) as 1 second. Plug these values into the equation d = (1/2)at^2 and solve for the acceleration (a).
- After finding the acceleration, you can use it to find the depth of the shaft by substituting the known values into the equation d = (1/2)at^2.
4. Solve the second problem:
- The rocket starts from rest, so its initial velocity (v1) is zero.
- You are given the acceleration (a) as 4 m/s^2 and the time (t) as 10 seconds. Plug these values into the equation d = (1/2)at^2 and solve for the distance traveled (d).
5. Incorporating gravity: In the problems you mentioned, the effect of gravity needs to be considered. The acceleration due to gravity (g) is usually taken as 9.8 m/s^2. However, gravity is not relevant to solving these specific problems because the given information does not involve it.
Remember, it's crucial to understand the concepts and equations to solve physics problems accurately. Practice using these equations and seek guidance if needed.