Register to reply

Impulse and Momentum: Substitution Trouble

by Sakura
Tags: impulse, momentum, substitution, trouble
Share this thread:
Sakura
#1
Mar16-06, 05:43 PM
P: 4
Ok, in this problem I am getting bogged down in the basic algebra part of it. I had one person explain it once but I still missed something.

a 1055-kg van, stopped at a traffic light, is hit directly in the rear by a 715-kg car traveling with a velocity of +2.26 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity of (a) the car and (b) the van?
m1 = 715 kg
m2 = 1055 kg
vo1 = +2.25 m/s
vo2 = 0 m/s
vf1 = ?
vf2 = ?
Phys.Org News Partner Science news on Phys.org
Fungus deadly to AIDS patients found to grow on trees
Canola genome sequence reveals evolutionary 'love triangle'
Scientists uncover clues to role of magnetism in iron-based superconductors
GregA
#2
Mar16-06, 06:07 PM
P: 213
You know the initial masses and velocities and hence the initial momentum...from this you know the *relative* approach velocity before impact...and as the collision is elastic you also know the relative exit velocity...If you can form 2 equations using this info you should be able to spot a substitution easily...I don't think trying to solve in terms of KE is the best method
Da-Force
#3
Mar16-06, 06:23 PM
P: 70
The initial momentum of the system (the car + the van) must equal the final momentum of the system (the car + the van).

Treat velocities as vectors such that -> would be (+) and <- would be (-).

That should help.

Sakura
#4
Mar16-06, 07:05 PM
P: 4
Impulse and Momentum: Substitution Trouble

AHHH... thank you! lol makes more sense that way!!
Da-Force
#5
Mar16-06, 08:13 PM
P: 70
No problem.


Register to reply

Related Discussions
Impulse and momentum Introductory Physics Homework 5
Momentum, Impulse and consevation of momentum? Calculus & Beyond Homework 1
Substitution for impulse in recurrence equation Differential Equations 0
Work done by the hammer in a single stroke? Introductory Physics Homework 1