1.3 COLLISIONS, EXPLOSIONS AND IMPULSE Flashcards
1
Q
Conservation of momentum
A
In the absence of net external force, total momentum before=total momentum after
2
Q
A collision is
A
an event, interaction when two objects apply a force to each other for a relatively short time
3
Q
IF Ek is conserved
A
the collision is elestic
4
Q
If Ek is not conserved
A
the collision is inelastic
5
Q
before using the conversation of momentum …
A
make sure about the direction of each velocity
6
Q
Explosion
A
p before= o
7
Q
Newton’s Third Law and momentum
DURING NORMAL COLLISION
A
- m1u1+m2u2=m1v1+m2v2 therefore
(-m1(v1-u1)/t = (m2(v2-u2)/t and
-m1a1= m2a2
-F1=F2
8
Q
Newton’s Third Law amd Momentum
explosion
A
0=m1v1+m2v2
m1a1=-m2a2
F1=-F2
9
Q
IMPULSE
Ns or kg m s-1
A
Ft=mv-mu (CHANGE IN MOMENTUM) or area on the graph : 1/2 ab
10
Q
Airbags and crample zones
A
decrease force and increase time
