Δt=6.7 s, Δx= .25 miles what is speed?

• burton95
In summary, the conversation discusses a dragster starting from rest and traveling 0.25 miles in 6.7 seconds. The problem asks to find the speed of the dragster in miles per hour, assuming constant acceleration. The conversation then goes on to discuss relevant equations and variables needed to solve the problem, including the conversion of miles to meters and the use of the average velocity to find the final velocity.
burton95

Homework Statement

A dragster starts from rest and travels 0.25 miles in 6.7 s. Assuming that the acceleration is constant, what is its speed (in miles per hour) at this point?

Δt= 6.7 s
Δx= .25 miles

Homework Equations

Constant acceleration equations

v = vo + at

x = xo + vo t + ½ a t2

xo + ½ (v + vo) t

2 a (x - xo)= v2 - vo2

The Attempt at a Solution

all of the relevant constant acceleration equations I have in front of me have too many variables to isolate one given this. I know I can figure Vavg .25/0.00186111 hrs (6.7 s.) = 134.3284 but this doesn't do me any good. If you could nudge me in the right direction I would appreciate it.

There are only 2 things you don't know here, the acceleration and the final speed. All other things you do know. As the problem says the body starts moving from rest, so there's v0. Aside from that, you now it travels a distance of .25 miles, which all you need to now, simply define x0=0 which means Δx=x, and that's all. You should be able to solve the problem.

You need to convert miles to meters. Then you'll get acceleration using x = ½at^2 (it starts from rest so v0=0). Vfinal=at

so in Δr = vΔt + (1/2)a(Δt)2 the vis v0? This was not clear. Thanks

burton95 said:
so in Δr = vΔt + (1/2)a(Δt)2 the vis v0? This was not clear. Thanks
Yes. Since the car starts from rest, the equation simplifies to x = ½at^2.

Yes, in that equation, the v is the inicial velocity of the body, usually named v0.

lep11 said:
You need to convert miles to meters. Then you'll get acceleration using x = ½at^2 (it starts from rest so v0=0). Vfinal=at

Actually, you don't have to convert miles to meters.

Also, if the acceleration is constant, then the average velocity is half the final velocity. The OP already calculated the average velocity. So...

Chet

1. What do the values of Δt and Δx represent?

The values of Δt and Δx represent the change in time and change in distance, respectively. In other words, Δt is the time interval between two points and Δx is the distance traveled during that time interval.

2. How do you calculate speed using Δt and Δx?

To calculate speed using Δt and Δx, you can use the formula: speed = Δx/Δt. In this case, the speed would be 0.25 miles/6.7 seconds, which is approximately 0.037 miles per second.

3. Is the speed a constant value in this scenario?

No, the speed is not a constant value in this scenario. It is the average speed over the given time interval of 6.7 seconds. The actual speed may have varied during that time interval.

4. What are the units for speed in this calculation?

The units for speed in this calculation are miles per second (mi/s). This unit is commonly used for measuring the speed of objects in motion.

5. Can you convert the speed to a different unit of measurement?

Yes, the speed can be converted to a different unit of measurement. For example, if we wanted to convert the speed from miles per second to miles per hour, we would multiply the value by 3600 (the number of seconds in an hour). In this case, the speed would be approximately 0.037 miles per second x 3600 seconds = 133.2 miles per hour.

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