Copy down this Momentum table

Transcription

1 Copy down this Momentum table Objects P before (kg*m/s) P after (kg*m/s) Object 1 Object 2 Total

2 Announcements Quiz on Monday (All content from this week)

3 Momentum Objectives (Mom. and Energy Unit) 1. Define and calculate the momentum of an object. 2. Determine the impulse given to an object. 3. Interpret and use force vs. time graphs (Base x Height). 4. Apply conservation of momentum to solve a variety of problems. 5. Distinguish between elastic and inelastic collisions.

4 Elastic vs Inelastic Collisions and Explosions Elastic Collisions are collisions where two objects bounce off of each other Inelastic Collisions are collisions in which two objects collide and stick to each other Explosions result from a single object being broken up into two or more parts

5 Using tables to Solve Word Problems Objects P before (kg*m/s) P after (kg*m/s) Object 1 Object 2 Total

6 Example 1 elastic collision A 2000-kg car traveling at 20 m/s collides with a 1000-kg car at rest at a stop sign. If the 2000-kg car has a velocity of 6.67 m/s after the collision, find the velocity of the 1000-kg car after the collision.

7 A 2000-kg car traveling at 20 m/s collides with a 1000-kg car at rest at a stop sign. If the 2000-kg car has a velocity of 6.67 m/s after the collision, find the velocity of the 1000-kg car after the collision. Objects P before (kg*m/s) P after (kg*m/s) Car A Car B Total

8 A 2000-kg car traveling at 20 m/s collides with a 1000-kg car at rest at a stop sign. If the 2000-kg car has a velocity of 6.67 m/s after the collision, find the velocity of the 1000-kg car after the collision. Objects P before (kg*m/s) P after (kg*m/s) Car A (2000)(20) = 40,000 Car B (1000)(0) = 0 Total 40,000

9 A 2000-kg car traveling at 20 m/s collides with a 1000-kg car at rest at a stop sign. If the 2000-kg car has a velocity of 6.67 m/s after the collision, find the velocity of the 1000-kg car after the collision. Objects P before (kg*m/s) P after (kg*m/s) Car A (2000)(20) = 40,000 (2000)(6.67) = 13,340 Car B (1000)(0) = 0 (1000)(VB) = 1000VB Total 40,000 13, VB

10 Example 1: Problem (step 2: solving) (1) Table Objects Pbefore (kg*m/s) Car A (2000)(20) = 40,000 Car B (1000)(0) = 0 Pafter (kg*m/s) (2000)(6.6 7) = 13,340 (1000)(VB) = 1000VB Total 40,000 13, VB (2) Math to solve for final Vb P before = P after 40,000 = 13,340 + (1000)Vb 26,660 = 1000Vb 26.7 = Vb Vb = 26.7 m/s

11 Example 2 inelastic collision On a snow-covered road, a car with a mass of 1100 kg collides head-on with a van having a mass of 2500 kg traveling at 8 m/s. As a result of the collision, the vehicles lock together and immediately come to rest. Calculate the speed of the car immediately before the collisions. [Neglect friction]

12 On a snow-covered road, a car with a mass of 1100 kg collides head-on with a van having a mass of 2500 kg traveling at 8 m/s. As a result of the collision, the vehicles lock together and immediately come to rest. Calculate the speed of the car immediately before the collisions. [Neglect friction] Pbefore (kg*m/s) Pafter (kg*m/s) Car Van Total

13 On a snow-covered road, a car with a mass of 1100 kg collides head-on with a van having a mass of 2500 kg traveling at 8 m/s. As a result of the collision, the vehicles lock together and immediately come to rest. Calculate the speed of the car immediately before the collisions. [Neglect friction] Pbefore (kg*m/s) Pafter (kg*m/s) Car 1100*Vcar = 1100Vcar Van 2500*(-8) = -20,000 Total 1100Vcar 20,000

14 On a snow-covered road, a car with a mass of 1100 kg collides head-on with a van having a mass of 2500 kg traveling at 8 m/s. As a result of the collision, the vehicles lock together and immediately come to rest. Calculate the speed of the car immediately before the collisions. [Neglect friction] Pbefore (kg*m/s) Pafter (kg*m/s) Car 1100*Vcar = 1100Vcar Van 2500*(-8) = -20,000 ( )(0) = 0 Total 1100Vcar 20,000 0

15 Example 2: Problem (step 2: solving) (1) Table Pbefore (kg*m/s) Car 1100*Vcar = 1100Vcar Van 2500*(-8) = - 20,000 Total 1100Vcar 20,000 Pafter (kg*m/s) 0 0 (2) Math to solve for final V Pb = Pa 1100Vcar 20,000 = 0 Vcar = 20,000/1100 Vcar = 18.2 m/s

16 Example 2 inelastic collision On a snow-covered road, a car with a mass of 1100 kg collides head-on with a van having a mass of 2500 kg traveling at 8 m/s. As a result of the collision, the vehicles lock together and travel to at 3 m/s. Calculate the speed of the car immediately before the collisions. [Neglect friction]

17 Example 3 explosion A 4-kg rifle fires a 0.02-kg shell with a velocity of 300 m/s. Find the recoil velocity of the rifle.

18 A 4-kg rifle fires a 0.02-kg shell with a velocity of 300 m/s. Find the recoil velocity of the rifle. Pbefore (kg*m/s) Pafter (kg*m/s) Rifle Shell Total

19 A 4-kg rifle fires a 0.02-kg shell with a velocity of 300 m/s. Find the recoil velocity of the rifle. Pbefore (kg*m/s) Pafter (kg*m/s) Rifle Shell (4+0.02)(0) = 0 Total 0

20 A 4-kg rifle fires a 0.02-kg shell with a velocity of 300 m/s. Find the recoil velocity of the rifle. Pbefore (kg*m/s) Pafter (kg*m/s) Rifle Shell 0 4*V recoil (.02)(300) = 6 Total V recoil

21 Example 3: Problem (step 2: solving) (1) Table Pbefore (kg*m/s) Pafter (kg*m/s) (2) Math to solve for final V Pb = Pa Rifle 4*V recoil 0 Shell (.02)(300) = 6 0 = 6 + 4V recoil V recoil = -6/4 = V recoil = m/s Total V recoil