Hello guys,

is there anyone who can help me with this motion question

I know how do it but I don't know why they do it like this

I'll write my question

An identical rocketrthat provides a constant force of 22 N (acceleartion=34 m/s/s) is now launched horizontally from the top of a 50 m tall bulding. Assume that in its subsequent motion the rocket always points horizontally. After 1.5 s what is the speed of the rocket. and at what angle is the rocket moving relative to the ground. I got the answers. The speed is 68 and the angle is 12 degress. You can get that from working out the vertical and horizontal components in the force. But how can there be a vertical component in this question.

 

Any help would be seriously appreciated!!

Edited June 6, 200817 yr by scilearner
pasted from IRC on request.

You obviously had a vertical component to get the answer. What was it?

You obviously had a vertical component to get the answer. What was it?

 

 

No the question was just phrased like that. In the answer they have worked out the vertical component. You know like a projectile motion question. They have taken for vertical u=0 a=-10 t=1.5

 

v=u+at

= 15 m/s

 

They they worked out horizontal and used pythagorous therorm to work out the resultant vector. But in the question it says the rocket is always pointing horizontally so isn't the answer just the horizontal component?

 

V=u+at

= 0 + 34*1.5

= 66 m/s

 

But in the question it says the rocket is always pointing horizontally so isn't the answer just the horizontal component?

 

 

 

I THINK that means that the horisontal acceleration is constant - i.e. the 22N force is always horisontal and doesn't start to angle down towards the ground as the rocket tilts. Otherwise the question would be alot more complicated.

a=-10

 

What does that indicate the acceleration is (I'd expect it to be 9.81 but 10 is often used)?