- #1
azn4life1990
- 7
- 0
Homework Statement
A package of mass m is released from rest at a warehouse loading dock and slides down a 3.0-h frictionless chute to a waiting truck. Unfortunately, the truck driver went on a break without having removed the previous package, of mass 2m, from the bottom of the chute.
a) suppose the packages stick together. what is their common speed after the collision?
b) suppose the collision between the packages is perfectly elastic. to what height does the package of mass m rebound?
Homework Equations
KE = PE
KE = 1/2 mv2
PE = mgh
The Attempt at a Solution
Vi = 0m/s
Ek = Ep
1/2mv2 = mgh
The masses cancel each other out, leaving me with
v = [tex]\sqrt{}2gh[/tex]
v = 58.8m/s, this is the velocity at which the box 1 hits box 2
From this point i decided to use momentum to find the final velocity
(2m+m)vf = mvi
This simplifies to 3Vf = V/3 = 19.6m/s
Why would using momentum be flawed?
When I use KE is conserved throughout this system I get another answer... that is why one of the methods I'm using is wrong
1/2mv2 = 1/2mv2
1/2(2m+m)v2 = 1/2mv2
Doing some algebra I get that V2 = V2/3
For this answer the Vf = 33.95m/s