Applying Newton's 2nd Law

Thursday Nov. 30 and Friday Dec. 1
We did a short recap today of where we have come since September...lots of good learning had gone on! The short version is...CVM (Constant Velocity Model), BFM (Balanced Force Model), CAM (Constant Acceleration Model) which brings us to the topic for today...

UBFM---Unbalanced Force Model
 
This is what happens when the forces on an object are not balanced and accelerated motion is the result...just like our rockets. We did an example in class of finding the thrust that a rocket exerts using Newton's 2nd Law:
Fnet = ma
 
Students were given Q2HW#2 and started working on it in class. Here are the answers:
 
1b) 220 N right 1c) 1.1 m/s2  1d) 1960 N down 1e) 1960 N up by ground
2a) 42.5 N 2b) 49 N down 2c) 91.5 N up
3) 833 N down 3b) -333N or 333N down 3c)-3.9 m/s2 or 3.9 m/s2 down
4a) 735 N 4b) 415 N 4c) 5.53 m/s2
5a) 10 m/s2  5b) 10 m/s2  5c) 10 m/s2
6) 6 m/s2
7) Pulling force = 296 N...bag will rip
8) 2.07 m/s2
9) Tension = Fnet = 116.6 N
10) 22.4 m/s2
11a) 3000 N 11b) 4.2 m/s2
12) 3.89 m/s2
13) 1936 N
14) 3.65 m/s2
Quiz next week!

Section A

Section B

Section C