#### Archived

This topic is now archived and is closed to further replies.

# Physics help!!!

This topic is 5829 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

I can''t figure out this quiz question: Consider a minor parking-log accident. Car A backs out at 30 cm/s toward the west, and car B looks for a place to park, driving at 40 cm/s. Both cars mass 1,000 kg. What is the total system momentum before the collision? Remember that momentum is a vector quantity. Also, be careful with your units. I could''ve sworn the answer was the sum of both vectors which I thought was: 700 kg*m/s, generally northwest. The answer key told me without explanation that it''s 500 kg*m/s, generally northwest. Where in the world did they get 500 from? Please help me out. -Lewis [m80] Play QUADz MX @ www.m80produxions.com

##### Share on other sites
it seems that you just added the two vectors to get to the 700 (30+40 ..) but the resulting vectors length is sqrt(x^2+y^2). with this you get to the 500

Runicsoft -- home of my open source Function Parser and more

##### Share on other sites
Thanx man... so i guess it boiled down to a simple trig problem. I have to think more open minded about these problems, I guess. I must've read somewhere that to get the total momentum in a system, you had to get the sum of the momentum in that system.

I guess I didn't read that line in the question that alerts us that we are using vectors. I totally forgot about the resultant.

Thanx again... I can sleep now.

-Lewis [m80]
www.m80produxions.com

[edited by - LewieM80 on December 27, 2002 1:11:57 PM]

##### Share on other sites

(Everybody gets that part confused at first)

##### Share on other sites
OK,

Wish I caught this sooner. This is clearly a homework question that basically asks for an answer. This type of question is not acceptable to the forum policy, see the FAQ below:

Forum FAQ

Graham Rhodes
Senior Scientist
Applied Research Associates, Inc.

##### Share on other sites

This topic is 5829 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

This topic is now closed to further replies.

1. 1
2. 2
Rutin
19
3. 3
khawk
19
4. 4
5. 5
A4L
11

• 9
• 12
• 16
• 26
• 10
• ### Forum Statistics

• Total Topics
633771
• Total Posts
3013762
×