need physics help

[Sub-Zero]

A 500 g model rocket is on a cart that is rolling to the right at a speed of 3.0 m/s. The rocket engine, when it is fired, exerts an 8.0 N thrust on the rocket. Your goal is to have the rocket pass through a small horizontal hoop that is 20 m above the launch point.

At what horizontal distance left of the loop should you launch?

 

[PICK3]

lol! at the symbology

rockets & loops

 

[cwc73]

does the rocket fire straight up? If so, I think I might be about to figure it out. Just remember independent X/Y directions.

 

[Sub-Zero]

nimbus helped me out, thanks guys

 

[jerkbox]

i'll thrust a rocket through your loop bitch

 

[Tiervexx]

A 500 g model rocket is on a cart that is rolling to the right at a speed of 3.0 m/s. The rocket engine, when it is fired, exerts an 8.0 N thrust on the rocket. Your goal is to have the rocket pass through a small horizontal hoop that is 20 m above the launch point.

At what horizontal distance left of the loop should you launch?

assuming that the rocket keeps moving to the right at 3.0 m/s after launch you first calculate the time it takes for the rocket to travel 20m.

Acceleration is F = MA, 0.5 KG for mass, and Force is 8 N so A is 16 m/s.

So functions for movement are:

a(t) = 16
v(t) = 16t
p(t) = 8t^2

Solve for p(t) = 20

t = 1.58 seconds.

Next question is how far will the cart move to the right in 1.58 seconds?

Answer is 1.58*3 = 4.74 meters.

I realize this might be too late but I wanted to see if I could remember how to do this stuff because I have not seen such problems in years.

 

[all the whey]

 

[nimbus]

assuming that the rocket keeps moving to the right at 3.0 m/s after launch you first calculate the time it takes for the rocket to travel 20m.

Acceleration is F = MA, 0.5 KG for mass, and Force is 8 N so A is 16 m/s.

So functions for movement are:

a(t) = 16
v(t) = 16t
p(t) = 8t^2

Solve for p(t) = 20

t = 1.58 seconds.

Next question is how far will the cart move to the right in 1.58 seconds?

Answer is 1.58*3 = 4.74 meters.

I realize this might be too late but I wanted to see if I could remember how to do this stuff because I have not seen such problems in years.

you forgot to subtract the accel due to gravity from the accel of the thrust, ohhhhhhhhh

 

[swole]

i turn thug chicks into ladies

 

[redguru]

you forgot to subtract the accel due to gravity from the accel of the thrust, ohhhhhhhhh

Always draw a vector diagram.

 

[sardonicone]

Damnit, I'm late to the party.

 

[needtogetaas]

4.70meters

 

[redguru]

assuming that the rocket keeps moving to the right at 3.0 m/s after launch you first calculate the time it takes for the rocket to travel 20m.

Acceleration is F = MA, 0.5 KG for mass, and Force is 8 N so A is 16-9.8 m/s^2.

So functions for movement are:

a(t) = 16-9.8=6.2
v(t) = 6.2t
p(t) = 3.1t^2

Solve for p(t) = 20

t = 2.5 seconds.

Next question is how far will the cart move to the right in 1.58 seconds?

Answer is 2.5*3 = 7.5 meters.

I realize this might be too late but I wanted to see if I could remember how to do this stuff because I have not seen such problems in years.

I like how you took the derivatives of position and velocity, but I think he is still in a non-calculus based physics.

 

[redguru]

4.70meters

It's 7.5 meters to 2 sig figs.

 

[redguru]

Oh, and Fuck You Samoth. I knew you'd click on this.

 

[juiceddreadlocks]

Oh, and Fuck You Samoth. I knew you'd click on this.

aint that the truth

 

[samoth]

Oh, and Fuck You Samoth. I knew you'd click on this.

God dammit!

 

[Tiervexx]

you forgot to subtract the accel due to gravity from the accel of the thrust, ohhhhhhhhh

Normally they would say "assume the gravity constant of X" or whatever, this problem did not.

I actually thought about that but forgot to make a note of it.

 

[Tiervexx]

I like how you took the derivatives of position and velocity, but I think he is still in a non-calculus based physics.

for me this was always the natural way to do it because I took calc before physics, but I can see how that might be an issue, I never remembered those formulas though =P

 

[gonelifting]

"True"... I mean "False". My answer is "False".


A rocket can NOT loop.

 

[Tiervexx]

"True"... I mean "False". My answer is "False".


A rocket can NOT loop.

LOL, this reminds me of what my calc teacher told us to do on the AP test if we did not understand a problem.

Just take a derivitive and set it equal to something...chances are that will be part of the answer.