Homework Help: physics 20

Posted by Adrienne on Tuesday, November 3, 2009 at 10:08pm.

A speed velocity of a a rocket with a mass of 0.25 kg passes from 15 m/s[up] to 40 m/s[up] in 0.60s. calculate the force of the escaped gasses of the rocket.
****

that's what i've done, so far

data: m = 0.25kg
initial velocity = 15 m/s
final velocity = 40 m/s
time = 0.60s

final velocity - initial velocity / time = acceleration

40 m/s - 15 m/s / 0.60 s = 41.67 m/s^2

for here the solutions for the problem says that the next formula that needs to be used is FORCE = MASS (GRAVITY + ACCELERATION) why is that.
and why would you not use the formula
force = mass x acceleration ?

physics 20 - Jordan, Wednesday, November 4, 2009 at 7:58am
acceleration due to gravity must be factored in as the rocket is traveling upwards. since you have chosen up to be positive acceleration down must be negative, making gravity -9.8m/s

the equation is still
force=mass x acceleration
accept the formula used to calculate acceleration does not factor in gravity, the value calculated will just assume that no other forces are acting on the rocket

i know this may not be the best clarification so ask away with any problems :)

Answer this Question

Related Questions

physics 20 - A speed velocity of a a rocket with a mass of 0.25 kg passes from ...
physics - A box whose mass is 20 kg rests on a frictionless ramp with a 15 ...
Physics - With the engines off, a spaceship is coasting at a velocity of +210 m/...
physics - A rocket carrying a satellite is accelerating straight up from the ...
Physics - A child in a boat throws a 5.40 kg package out horizontally with a ...
Physics - A book whose mass is 3 kg is projected up a long 40 degree incline ...
physics - A model rocket is constructed with a motor that can provide a total ...
PHYSICS - A model rocket is constructed with a motor that can provide a total ...
Physics - You launch a model rocket up into the sky. Right after launch the ...
physics - You launch a model rocket up into the sky. Right after launch the ...

For Further Reading

First Name:
School Subject:
Answer: