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Impulse and Momentum. 9.1 Momentum and Impulse 9.2 Solving impulse and momentum problems 9.3 Conservation of momentum 9.4 Explosions 9.5 Inelastic Collisions 9.6 Momentum in two Dimension 9.7 Angular Momentum. Collision. The rapidly changing magnitude Of the force during collision.
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Impulse and Momentum 9.1 Momentum and Impulse 9.2 Solving impulse and momentum problems 9.3 Conservation of momentum 9.4 Explosions 9.5 Inelastic Collisions 9.6 Momentum in two Dimension 9.7 Angular Momentum
Collision The rapidly changing magnitude Of the force during collision
Stop to think 9.1 P244Stop to think 9.2 P247Stop to think 9.3 P253Stop to think 9.4 P255Stop to think 9.5 P257 • Example 9.1 P245 • Example 9.3 P250 • Example 9.4 P251 • Example 9.6 P254 • Example 9.9 P259
Momentum • Fx(t) = max(t)= m(dVx)/dt • We define: • Momentum = • Momentum is a vector It’s x-component and y-component are
Impulse • From above: • Impulse is equal to momentum change • We define: • Impulse
Quick think What is the cart’s change of momentum ? 30kgm/s
Ex.9.1 3000N
Momentum Bar Charts • From
Conservation of Momentum The sum of the momentum does not change Ie. The sum of the momentum after the Collision equals the sum of the momentum Before the collision. T
Law of conservation of momentum • The total momentum of an isolated system is a constant. Interactions within the system do not change the system’ momentum.
Objects A and C are made of different materials, with different ‘springiness’, but they have the same mass and initially at rest.When ball B collides with object A, the ball ends up at rest. When B is thrown with the same speed and collides with object C, the ball rebounds to the left. Compare the velocities of A and C after the collisions. Is Va Greater than, equal to, or less than Vc.
Explosions • An explosion, where the particles of the system move apart from each other after a intense interaction. • Ex. Recoil. A rifle firing a bullet • Before: the total momentum is zero • After: The total momentum is • From
Inelastic Collision • If, after collision, the energy does not conserve, this kind of collision is called as Inelastic collision. • Perfectly inelastic collision: A collision in which the two objects stick together and move with a common final velocity. Ex. Bullet embedding itself in the wood. • The law of conservation of momentum for perfectly inelastic collision
Ex. 9.8 Momentum in a car cracsh (1) Find the deceleration from V1x to stop (2) Find the velocity V1x, using kinematics equation, this is the velocity after collision. (3) Find velocity of Volkswagen before collision using the law of momentum conservation
Momentum in Two Dimensions • Momentum conservation involve motion in a plane • Each component of momentum is conserved
Angular momentum • Angular momentum is defined as L = rmv Law of conservation of angular momentu The angular momentum of a particle (or system of particles) in circular motion does not change unless there is a net torque.