Trouble calculating the acceleration

[ERAUin08]

Hey everyone I need some help with a problem. I am having trouble calculating the acceleration since I don't the the initial velocity.

Homework Statement

You are driving on the highway when you come across a speedometer test where the distances are maked on signs. When you pass the 0 mile marker, rather than holding your speed constant you press on the accelarator and hold it constant. You pass the 0.1 mile marker 16 s later, and the 0.2 mile marker 8 seconds after the 0.1 marker. a) What did you speedometer read at the 0.2 mile? b) what was your acceleration?

Homework Equations

d=v/t
d=0.2 miles=322m
time=24 s

The Attempt at a Solution

a) 322m=v/24s
V=13m/s
b) For the acceleration I am not sure.

Thank you for your help

 

[Dick]

If it's accelerating you CAN'T use v=d/t (and you can't use d=v/t anywhere. It's wrong). You have to use d=v0*t+(1/2)*a*t^2 where v0 is the initial velocity and a is the acceleration. Now if you put in the two given time points, you have two equations in the two unknowns v0 and a. Solve for them.

 

[baba89]

!

Hello, it seems like you have correctly calculated the speed at the 0.2 mile marker. To calculate the acceleration, we can use the formula a = (vf - vi)/t, where vf is the final velocity, vi is the initial velocity, and t is the time. In this case, we know that vf = 13 m/s and t = 24 s. However, we do not have the initial velocity.

Since the question mentions that you pressed on the accelerator and held it constant, we can assume that your initial velocity was 0 m/s. This means that your acceleration would be (13 m/s - 0 m/s)/24 s = 0.54 m/s^2.

Alternatively, if you want to double check your answer, you can use the formula a = (v^2 - u^2)/2d, where v is the final velocity, u is the initial velocity, and d is the distance traveled. In this case, we know that v = 13 m/s, u = 0 m/s, and d = 322 m. Plugging these values in, we get a = (169 - 0)/644 = 0.54 m/s^2.

I hope this helps and good luck with your calculations!