Average speed & average velocity Problem

davidco

1. The problem statement, all variables and given/known data
Brandon is climbing a mountain. He starts from an elevation of H1=511m above sea level. In 6.18 hours he climbs to an elevation of H2=2746m above sea level. The length of his path is L1=16000m.

A)What is the average angle of ascent the path makes with the horizontal?Theta=
B)What is his average speed along the path in meters/second? average speed=
C)What is his average vertical velocity? Vup=
D)After he eats he hikes back down to their starting point in T2=4.24 hours
What is his average vertical velocity? Vdown=

2. Relevant equations
avg speed=total distance/total time
avg velocity=v=Delta x/delta t
tan theta=opposite/adjacent


3. The attempt at a solution

A)tan theta=opposite/adjacent
Im so confused as to what equations to use.

B)avg speed= total distance/total time

16000M/22680S=0.705m/s


C)avg velocity=v=Delta x/delta t

D)Confused on D as well

Please give some suggestions or the correct equations will be great.thanx Dave

hotvette

You are on the right track. If you haven't done it already, one thing that helps is to draw a picture.

For a, you have the correct equation. Hint: what does L1 represent in a simple idealized geometric shape?

For c & d: be careful. The problem says average vertical velocity.

Also, looks like you double posted by mistake.

davidco

Hotvette thanx alot for the help just got a few more questions.

If your talking in terms of a triangle L1 would represent my hypotenuse I believe. So would 16000m be my hypotenuse is what your suggesting. But dont I have to choose the equation involving the hypotenuse to find the angle. Like:

sin theta= opp/hyp
or
cos theta= adj/hyp

But my question is what is the equation for vertical velocity?

Thanx Vette

learningphysics

For the angle yes, use:

sin theta = opp/hyp

average vertical velocity = vertical displacement/time

davidco

Thank you learn,


But im wondering if my hyp=16000m and im trying to find theta. whats my opp or how do i find my opp.?

learningphysics

What distance does he travel vertically? they give you initial height and final height...

davidco

Thanx Learn,



Ok so if I subtract the H2=2746m- 511m=my distance is 2235m

So to find theta I did this:

sin theta=opp/hyp

sin theta=2235m/16000
theta=7.98 degrees or 8 degrees

Please tell me this is correct

learningphysics

yup, looks right to me. But I get 8.03 degrees.

davidco

Thanx,

For my average speed =total distance/total time,do I use the 16000m for total distance/6.18hrs or do i convert hrs to seconds. Since my answer has to be in m/s?

learningphysics

Yeah, I think converting to s is best. otherwise your answer will be in m/hr... best to use m/s.

davidco

Question so if vertical speed= deltaV/T,would my deltaV= .705m/s?I got .705m/s from my average velocity equation which was 16000m/22680s=.705m/s for avgV. Is average vertical velocity and vertical velocity the same equation?

learningphysics

vertical velocity is vertical displacement which you know is 2235m divided by time.