Acceleration, Solve for time (Algebra Based)

In summary, the average person passes out an acceleration of 7g, and if a car were designed to accelerate at this rate, it would take approximately 0.385 seconds to accelerate from rest to 60 miles per hour. However, this calculation is based on an exaggeration of the car's speed and may not be entirely accurate.
  • #1
Dig
13
0

Homework Statement


22. The average person passes out an
acceleration of 7g (that is, seven times the
gravitational acceleration on Earth).
Suppose a car is designed to accelerate at
this rate. How much time would be
required for the car to accelerate from rest
to 60.0 miles per hour? (The car would need
rocket boosters!)

Homework Equations


The Attempt at a Solution


v1 = 60
v0 = 0
a = 7 * 9.8 => 68.6m/s^2

a = change in velocity/change in time

So, 68.6m/s^2 = 60mph/t
68.6 * t = 60mpg
t = 60/68.6
= 0.87 seconds

I am not sure if this is correct or not.
The answer seems within reason since a very high powered sports car accelerates from 0-60 miles per hour in around 3 seconds, so 0.87 seconds would line up well with the exaggeration of the speed of the car mentioned at the end of the word problem.

Any help is appreciated :).
 
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  • #2
You are mixing English and SI units.
 
  • #3
edziura said:
You are mixing English and SI units.

Care to elaborate on where I went wrong and what I can do to correct my problem?
 
  • #4
Dig.
What he/she meant was that you are using G's (or 9.8m/s2) which is the acceleration on Earth in metric, and then Miles per hour, which is SI.

To fix this, take the MPH and multiply by .44 (or to be more exact, .44704) to get meters/second

By the way, the way to get the .44 is roughly 1600 meters/3600seconds = .44 (mile/hour hour=60 minutes=60 seconds. so 602)

This should give you some help, or at least point you in the correct direction.

Your equation is correct though.
 
Last edited:
  • #5
lax1113 said:
Dig.
What he/she meant was that you are using G's (or 9.8m/s2) which is the acceleration on Earth in metric, and then Miles per hour, which is SI.

To fix this, take the MPH and multiply by .44 (or to be more exact, .44704) to get meters/second

By the way, the way to get the .44 is roughly 1600 meters/3600seconds = .44 (mile/hour hour=60 minutes=60 seconds. so 602)

This should give you some help, or at least point you in the correct direction.

Your equation is correct though.


Alright, if I multiply 60mi/h by .44, I receive 26.4m/s. I divide this by 68.6m/s^2 to get an answer of .385s? Both the numerator and denominator have 3 significant digits, so I stop at .385 correct?

I see my mistake now. Thank you both for pointing that out to me.
 
  • #6
No problem Dig,
That seems correct to me.

Good luck in physics this year.
 
  • #7
lax1113 said:
No problem Dig,
That seems correct to me.

Good luck in physics this year.

Thank you so much :).
 

1. What is acceleration?

Acceleration is the rate at which an object's velocity changes over time. It is measured in meters per second squared (m/s²).

2. How is acceleration calculated?

Acceleration can be calculated by dividing the change in velocity by the change in time, using the formula a = (vf - vi) / t. Velocity is typically measured in meters per second (m/s) and time is measured in seconds (s).

3. What is the difference between average and instantaneous acceleration?

Average acceleration is the overall change in velocity over a given time period, while instantaneous acceleration is the acceleration at a specific moment in time.

4. How do you solve for time with acceleration?

To solve for time, we can use the formula t = (vf - vi) / a, where vf is the final velocity, vi is the initial velocity, and a is the acceleration. Plug in the known values and solve for time.

5. Can acceleration be negative?

Yes, acceleration can be negative. A negative acceleration, also known as deceleration, means that an object's velocity is decreasing over time.

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