Download presentation
Presentation is loading. Please wait.
1
Linear Momentum and Collisions
2
Momentum and Impulse m F m A block of mass (m) is acted upon by a force (F) After a time (D) the block acquires a velocity vf Momentum is conserved Momentum is a vector
3
Momentum and Impulse Newton’s 2nd Law p Using Calculus: Newton’s form of his 2nd law
4
v1 u1 Fm = - FM M m FM Fm M m v = u FmDt = - FMDt M m v2 u2 Dpm = - DpM m(u2 - u1) = -M(v2 - v1) Conservation of Momentum: Blocks have the same speed (v) at closest approach. mu2 - m u1 = - Mv2 + Mv1 Conservation of Momentum Mv1 + m u1 = Mv2 + mu2 p(before) = p(after)
5
before vo after M m v = ? M m Using the conservation of momentum to find the final speed when two blocks stick together.
6
after before v vo M m Find the speed of the bullet and block after impact.
7
Collisions Elastic Collisions Inelastic Collisions
Momentum and Kinetic Energy are both conserved Inelastic Collisions Elastic and Inelastic collisions A perfectly inelastic collision losses as much kinetic energy as possible Only Momentum is conserved
8
Perfectly Inelastic Collision
before v1 v2 after m1 m2 vf m1 m2 Find the final speed after a Perfectly Inelastic Collision Linear Momentum and Collisions.ppt
9
Elastic Collision (General Equations)
v1i v2i m1 m2 m2 m1 v1f v2f General Equations for an elastic collision. Velocity is a vector - use + and - to indicate directions.
10
Elastic Collision (v2i = 0)
m2 m1 v1i m2 m1 v1f v2f Special Case: Elastic collision with m2 initially at rest.
11
Elastic Collision (v2i = 0 and m1= m2)
V2f = V1i Special Case: Elastic collision with equal masses and with m2 initially at rest.
12
Ballistic Pendulum vo M h m v Ballistic Pendulum
Cons. Energy Cons. Momentum vo M m v Ballistic Pendulum Use conservation of momentum and energy.
13
Ballistic Pendulum Find the speed of the bullet vo M h m v
Cons. Momentum vo M m v
14
Ballistic Pendulum h Cons. Energy M v
15
Collisions in two dimensions
p1f p1i m1 m1 m2 p2f Linear Momentum and Collisions.ppt
16
Collisions in two dimensions
y p1i = m1v1i p1f = m1v1f p2f = m2v2f q f P1i = P1f + P2f x m1v1f cos(q) + m2v2f cos(f) = m1v1i m1v1f sin(q) + m2v2f sin(f) = 0
17
END ?
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.