Momentum-Impulse-and-Collision-W3 (1).pptx

Momentum, Impulse, and Collision for Science 9

1. Momentum and Impulse Relate impulse and momentum to collision of objects (e.g., vehicle collision)

2. Momentum Momentum refers to the quantity of motion that the object has. It is also known as the mass or the inertia in motion. Momentum of an object directly depends on its mass and velocity. The greater the mass, the larger is the momentum, provided that the velocity is held constant. If the mass is held constant, and the velocity is increased, momentum of the object also increased. This is one of the cases of changing momentum of an object.

3. Momentum Increasing the mass or increasing the velocity or even both, increases the momentum of the object. The relationship between momentum, mass and velocity can be written. In equation: p = m x v

4. Impulse Impulse is the quantity force multiplied by time is known as impulse (I) or the change in momentum (Δp) of the object. This also means that change in momentum is attained when a force is applied on the object over duration of time of contact. Increasing the force and time of contact would provide a large impulse. With a large impulse, a great change in momentum is attained by the object. This is usually observed in different sports. In equation: Δp = F ◦Δt, Δp = m Δ v, Δp = m x (V f – V i )

5. Example: Rieza and her friends are playing volleyball. Rieza started by serving the ball which has a mass of 0.26 kilograms. Naya fiercely spiked the volleyball with a velocity of 22.2 m/s. What is the ball’s momentum? Given: m = 0.26 kilograms v = 22.2 m/s Find: p Solution: p = m x v p = 0.26 kg x 22.2 m/s p = 5.8 N or kgm/s – momentum A 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces straight back at 2.0 m/s. Given: m = 1.0 kg V i = 4.0 m/s V f = -2.0 m/s Find (I) Solution: I = (1.0 kg) (-2.0 m/s - 4.0 m/s) I = - 6.0 kgm/s - Impulse

6. Collision Infer that the total momentum before and after collision is equal

7. Any interaction of particles in which momentum is exchanged or transferred is referred as collision . 2 Types of Collision Elastic collision - kinetic energy is conserved. In this collision, complete transfer of energy happens. Inelastic collision – kinetic energy is not conserved. Some of the kinetic energy is lost to other forms such as heat and sound. This results to a smaller final kinetic energy, than the initial kinetic energy.

8. Consider two billiard balls that have equal masses such as the cue ball and the 8 ball. Initially, the 8 ball is stationary and the cue ball is moving at a certain speed. After colliding, they move apart with different momenta with no loss of momentum. This is what is called a perfectly elastic collision . It is often shortened to an elastic collision where the kinetic energy of the system is completely conserved.

9. Categories Inelastic Collision Elastic Collision Momentum Conserved Conserved Kinetic Energy Not Conserved Conserved Newton’s third law of motion states that for every action, there is an equal but opposite reaction. Using the equivalent of force provided by the second law of motion (F= ma) will result to the product of the mass and acceleration of object. Take note that in any interaction the momentum of the system is the same. This is known as the law of conservation of momentum.

10. The Law of Conservation of Momentum States that “the total momentum of a system does not change when there are no external forces acting on it.”

11. Impulse and Impulse- Momentum Theory The change in momentum can happen in different ways. It could involve impulsive forces during collisions and crashes. Impulsive force is also known as the force of impact and is oftentimes a very large varying force that occurs in a short span of time. The physical quantity that describes what happens during a collisions or when the momentum changes is called impulse . Impulse is the product of the force of impact and the time that force is being applied.

12. Impulse and Impulse- Momentum Theory The impulse-momentum theory states that the impulse is equal to the change in momentum Impulse is not a momentum itself but the measure of how much the momentum changed. The impulse-momentum theory explains what happens over a small span of time involving forces that changes over time. What it approximates is the average force of impact, which is often greatest at the start and exponentially drops over time.

13. A car traveling down the road is slowed down slightly when the brakes are just gently tapped . The force of the brakes is exerted over a small time resulting in a small impulse and a small change in the momentum of the car.

14. Sample Problem: A 0.5 kg basketball initially moving at 5m/s had a perfectly elastic collision with a 5 kg bowling ball moving toward it. If the basketball after colliding moves in the opposite direction at 2m/s with the bowling ball following it at 0.3m/s, what is the initial velocity of the bowling ball?

15. Sample Problem: The given values for the initial momentum would be Mass of the basketball M 1 = 0.5 kg Velocity of the basketball V 1I = 5 m/s Mass of the bowling ball M 2 = 5 kg Velocity of the bowling ball = ? The given values after the collisions are Mass of the basketball M 1 = 0.5 kg Velocity of the basketball V 1f = - 2m/s Mass of the bowling ball M 2 = 5 kg Velocity of the bowling ball V 2f = - 0.3 m/s

16. Note: The values of the final velocity of the bowling ball and basketball are both negative because they are moving in the opposite direction or toward the left, which is the negative directions on the number line. P i = P f ( M 1i) ( V 1i) + ( M 2i) ( V 2i) = ( M 1f) ( V 1f) + ( M 2f) ( V 2f )