Help Solve Physics Problem: Rocket Acceleration in <60 mins

[mattmaka]

Urgent help needed on physics problem!

A rocket is launched straight up with constant acceleration. Four seconds after liftoff, a bolt falls off the side of the rocket. The bolt hits the ground 6.40 s later.

What is the rocket's acceleration?

I have less than an hour to answer this online, please help.

 

[mattmaka]

I have no idea how to relate the distances or anything. Any help in setting up equations would be great.

 

[vsage]

Ok I made a little mistake before. R is the rocket's acceleration so the displacement for the first 4 seconds is d0 = 0.5 * R * 4^2 = 8R. The velocity it gains during this time is equal to R*T = 4R

Now during the drop the displacement is given by d = d0 + v1*t + 0.5*(-g)*t^2

At t = 6.4 seconds d and d0 are equal. Subbing in some stuff and knowing that d = 0 after 6.4 seconds 0 = 8R + 4R*6.4 - 4.9*6.4^2. Solve for R.

 

[tony873004]

A rocket is launched straight up with constant acceleration. Four seconds after liftoff, a bolt falls off the side of the rocket. The bolt hits the ground 6.40 s later.

What is the rocket's acceleration?

I have less than an hour to answer this online, please help.

5.95 m/s^2

 

[Thaore0]

How did you get the answer tony?

 

[tony873004]

How did you get the answer tony?

I wrote a computer program, trying different values for a, until t = 10.4

Private Sub Command1_Click()
Dim a As Double, Vrocket As Double, Vbolt As Double, pRocket As Double, pBolt As Double
Dim t As Double, sstep As Double

sstep = 0.01
pRocket = 0
Vrocket = 0
a = 5.95

For t = 0 To 4 Step sstep
    Vrocket = Vrocket + a * sstep
    pRocket = pRocket + Vrocket
Next t

pBolt = pRocket
Vbolt = Vrocket
t = 4 + sstep

While pBolt > 0
    Vbolt = Vbolt - 9.81 * sstep
    pBolt = pBolt + Vbolt
    t = t + sstep
Wend
Text1.Text = t
End Sub

 

[Thaore0]

Sweet! Is that Visual Basic?

 

[tony873004]

Sweet! Is that Visual Basic?

Yes, VB 6.0. That's how I do the problems I can't quite understand. It's called a numerical solution. There are some problems where no analytical solution exists, and a numerical solution is necessary.

But I'm sure that an analytical solution exists for this problem, and I'm waiting to see if someone knows it. This is the type of problem I'm going to face in about 2 weeks. (And I'm not allowed to bring my laptop to tests )

 

[vsage]

Read my post above sorry I posted an incorrect solution before it's about 5.96.

 

[mattmaka]

thanks for the help guys.

 

[tony873004]

thanks for the help guys.

Did you get it right? I imagine you're using an instant grading homework system?