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Conservation of Momentum.pptx
- 1. 1. Explain how momentum is conserved. 2. Show how momentum before and after collision is equal.
- 2. Arrange the letters to form a comprehensible word.
- 3. IMPULSE
- 4. MOMENTUM
- 5. VELOCITY
- 6. MASS
- 7. FORCE
- 8. IMPULSE is a measurement of mass in motion MOMENTUM is a term that quantifies the overall effect of a force acting over time
- 9. IMPULSE is a term that quantifies the overall effect of a force acting over time MOMENTUM is a measurement of mass in motion
- 26. If the balloon has momentum in one direction, the air must have an equal and opposite momentum for the total momentum to remain zero.
- 27. Change in momentum = 0 Total Initial Momentum = Total Final Momentum 0 = pballoon+ pair -pballoon = pair -(mv)balloon = -(mv)air Since the mass of the balloon is greater than the mass of air, the velocity of the air must be greater in magnitude than the velocity of the balloon, and must be opposite in direction.
- 28. Suppose the entire world population gathers in one spot and at the sounding of a prearranged signal, everyone jumps up. While all the people are in the air, does Earth gain momentum in the opposite direction?
- 29. Take note that we should consider Earth and the people on it to be part of system for the total momentum to be conserved. The Earth also moves in the opposite direction. The change in momentum of the Earth is equal to that of the people but opposite in direction. Because of Earths large inertial mass, however, there is no perceptible change in motion.
- 30. Two ice skaters stand together. They push off and travel directly away from each other, the boy with a velocity of 1.50 m/s. If the boy weighs 735 N and the girl, 490 N, what is the girls velocity after they push off? (Consider the ice to be frictionless.)
- 31. Solution: Remember that W = mg, thus, m = W/g. MASS VELOCITY Boy 75 kg 1.50 m/s Girl 50 kg ?
- 32. 0 = pboy+ pgirl -pboy = pgirl -(mv)boy = (mv)girl -37.5 kg m/s = 50 kg (vgirl) -0.75 m/s = vgirl
- 33. Momentum is a vector quantity. It must have both magnitude (numerical value) and direction. The direction of the momentum vector is always in the same direction as the velocity vector. Like all vector quantities, momentum vectors can be added. For situations in which the two vectors are in opposite directions, one vector is considered negative and the other positive.
- 34. Two ice skaters stand together. They push off and travel directly away from each other, the boy with a speed of 0.50 m/s and the girl with a speed of 0.65 m/s. If the mass of the boy is 60 kg, what is the girls mass? (Consider the ice to be frictionless.)
- 35. Total Initial Momentum = Total Final Momentum 0 = pboy+ pgirl -pboy = pgirl -(mv)boy = (mv)girl 30.0 kg m/s = (mgirl) 0.65 m/s 46kg = mgirl
- 36. Two adjacent students stand on stationary skateboards, face each other, and push apart. The skateboarder on the left weighs 65 kg, the one on the right is 85 kg. If the lighter skateboarder moves at 3.2 m/s, determine the speed and direction of the heavier skateboarder.
- 37. As an assignment, list 3 ways by which knowledge of conservation of momentum can benefit you.
- 38. A collision is an encounter between two objects resulting in exchange of impulse and momentum. Because the time of impact is usually small, the impulse provided by external forces like friction during this time is negligible. If we take the colliding bodies as one system, the momentum of the system is therefore approximately conserved.
- 39. The total momentum of the system before the collision is equal to the total momentum of the system after the collision. total momentum before collision = total momentum after collision
- 40. The total momentum of the system before the collision is equal to the total momentum of the system after the collision. total momentum before collision = total momentum after collision
- 41. Collisions are categorized according to whether the total kinetic energy of the system changes. Kinetic energy may be lost during collisions when (1) it is converted to heat or other forms like binding energy, sound, light (if there is spark), etc. and (2) it is spent in producing deformation or damage, such as when two cars collide.
- 42. The two types of collision are: 1. Elastic collision one in which the total kinetic energy of the system does not change and colliding objects bounce off after collision. 2. Inelastic collision one in which the total kinetic energy of the system changes (i.e., converted to some other form of energy). Objects that stick together after collision is said to be perfectly inelastic.
- 47. In the Figure, a moving steel ball pendulum collides head-on with another steel ball. The collision is elastic, that is, the total kinetic energy of the system (2 steel balls) is the same before and after the collision.
- 48. The total momentum of the system before the collision is equal to the product of the first balls mass and velocity. The total momentum of the system after the collision must be equal to the total momentum before the collision.
- 49. The first ball comes to rest while the second ball moves away with a velocity equal to the velocity of the first ball. This is the case when the two balls have equal masses. The momentum of the first ball is transferred to the second ball. The first ball loses its momentum while the second ball gains momentum equal to that of the first balls momentum
- 50. What do you think would happen if you pull two balls away and release them at the same time? Why is it so?
- 51. Mass Velocity (before collision) Cart 1 0.30 kg 1.2 m/s Cart 2 0.50 kg 0
- 52. Mass Velocity (before collision) Cart 1 0.30 kg 1.2 m/s Cart 2 0.50 kg 0
- 53. Mass Velocity (before collision) Cart 1 0.30 kg 1.2 m/s Cart 2 0.50 kg 0
- 54. Since the two carts stuck together after collision, they have the same velocity after collision. The combined carts move at 0.45 m/s after the collision.