Question

Q. A 10.6 kg weather rocket generates a thrust of 226.0 N. The rocket, pointing upward, is clamped to the top of a vertical spring. The bottom of the spring, whose spring constant is 402.0 N/m, is anchored to the ground. Initially, before the engne is ignited, the rocket sits at rest on top of the spring.

A: After the engine is ignited, what is the rocket's speed when the spring has stretched 19.4 cm past its natural length?

B: What would be the rocket's speed after travelling the distance if it weren't tied down to the spring?

I did what u told me to do.
For A, F(net) = F(thrust)-mg
F(net)d = 1/2(k)(d^2)+ 1/2mv^2
and For B, Vf^2 = 2ad where a = F(net)/m I used 0.194m for d but both answers are wrong again. Do i used 0.194m for both in part a and b? If i do, i don't know why they are wrong.

Answer 1

dang. I forgot about PEnergy gain.

F(net)*d=1/2 kx^2+ 1/2 mv^2+mgx

sorry, It has been a long day for me (since three am).

check my thinking.

Answer 2

Its wrong again. is the value of d same as x??? I'm keep getting the wrong answers for both part a and b.

Answer 3

because there is PEnergy, i get the negative value do i can't take the root of it!!!