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View Full Version : Im not sure if this is the correct formula for this question, plz corect me


ImsoFly
Apr15-07, 02:41 PM
1. The problem statement, all variables and given/known data
hi this is the problem: the burning of the second stage of a two stage toy rocket takes the rocket from 12 m/s to 40 m/s in 5.0s. How far does the rocket during this time?


2. Relevant equations
would i use delta t= delta v/a ?

neutrino
Apr15-07, 02:51 PM
Yes, you would need to use that equation.

ImsoFly
Apr15-07, 02:52 PM
Thanks neutrino.. but would i do (40-12) to find the velcoity?

neutrino
Apr15-07, 02:58 PM
What are the 'knowns' in \Delta t = \frac{\Delta v}{a}? Substitute them and find the unknown.

ImsoFly
Apr15-07, 03:00 PM
the knowns are velocity and acceleration, yeah i know that you substitute them but would i do (40-12) to find the velcoity?
so like for (40-12) do i plug that in velocity together?

neutrino
Apr15-07, 03:04 PM
the knowns are velocity and acceleration

Are you sure about that?

Delta v is change in velocity = Final velocity - Initial Velocity = 40-12.

ImsoFly
Apr15-07, 03:09 PM
Are you sure about that?

Delta v is change in velocity = Final velocity - Initial Velocity = 40-12.

Yeah, so it's 23 but i was just saying...how would i put that in the formula in the proper way...

delta t= delta v/a, delta t= (40-12)/5.0s, delta t =28m/s /5.0s = 5.6s
therefore the rocket traveled for 5.6 s?

neutrino
Apr15-07, 03:14 PM
delta t= delta v/a, delta t= (40-12)/5.0s, delta t =28m/s /5.0s = 5.6s
therefore the rocket traveled for 5.6 s?

Units are important physics, and the Second is a unit of time.

It has already been stated in the problem that the rocket has been moving for 5 seconds when it's speed changed from 12 to 40 m/s. Acceleration is a measure of how velocity changes with time.

ImsoFly
Apr15-07, 03:16 PM
Units are important physics, and the Second is a unit of time.

It has already been stated in the problem that the rocket has been moving for 5 seconds when it's speed changed from 12 to 40 m/s. Acceleration is a measure of how velocity changes with time.

Okay...thanks for taking your time :rolleyes: