2. Rules of This Activity #1 All students must perform all of the work of the activity in their science journals even though you are working in your lab group. #2 When you are sure of your answer, transfer the information onto individual mini whiteboards. #3 The whiteboard work is to remain on the white board until it is approved.
3. Stating the Problem The mad scientist, Hugo A-go-go has developed a way to disrupt the electrical service to Chicago. The mass of the Eastbound (traveling to your right) CTA is 40,000 kg while the mass of the Westbound CTA is 30,000kg. The Eastbound transit is traveling at 20 m/s and the Westbound transit is traveling at 25 m/s. There are two separate, stationary cars also on the same track. They are 10,000 kg each.
5. What is the eastbound train’s momentum? P = mv Known Want m = 40,000 kg P (momentum) v = 20 m/s P = mv P = (40,000 kg )(20 m/s) P = 800,000 (kg)( m/s)
6. Working the Problem Draw a momentum vector diagram of the eastbound train. Place the tip of the arrow at (0, 0) coordinates.
7. Draw the Eastbound Train Momentum Vector Diagram N y W E S x 800,000 (kg)( m/s)
9. What is the westbound train’s momentum? P = mv Known Want m = 30,000 kg P (momentum) v = 25 m/s P = mv P = (30,000 kg )(-25 m/s) P = -750,000 (kg)( m/s)
10. Working the Problem Add the momentum vector of the westbound train to your vector diagram.
11. Add the Westbound Train Momentum Vector y x 800,000 (kgm/s) 750,000 (kgm/s)
12. Working the Problem What is the momentum of each of the stationary transits?
13. What is the momentum of each of the stationary transits? P = mv Known Want m = 10,000 kg P (momentum) v = 0 m/s P = mv P = (10,000 kg )(0 m/s) P = 0 (kg)( m/s)
14. Working the Problem The Eastbound train collides with one of the stationary transits. Draw a momentum vector diagram that represents the above scenario just before the collision.
15. Draw the Momentum Vector Diagram before the collision. y x 800,000 (kgm/s)
16. Working the Problem The Eastbound train collides with one of the stationary transits. Draw a momentum vector diagram that represents the above scenario just after the collision.
17. Net Momentum a collision= Net Momentum p collision y 800,000 (kg)( m/s)x
18. Working the Problem The Eastbound train collides with one of the stationary transits. Sticking together, they continue to roll along the track. What is their velocity after the collision?
19. Velocity after the Collision Net Momentum before = Net Momentum after Known Want me = 40,000 kg P before ve = 20 m/s v after ms = 10,000 kg vs = 0 m/s Pnet = (mv)net P = me ve + msvs P = (40,000 kg )(20 m/s) + (10,000 kg )(0 m/s) P = 800,000 (kg)( m/s) v = P/mv = 800,000 (kg)( m/s) / (40,000 kg ) + (10,000 kg ) v = 16 m/s E
20. Working the Problem The Westbound train collides with one of the stationary transits. Sticking together, they continue to roll along the track. What is their velocity after the collision?
21. Velocity after the Collision Net Momentum before = Net Momentum after Known Want mw = 30,000 kg P before vw = 25m/s v after ms = 10,000 kg vs = 0 m/s Pnet = (mv)net P = mw vw + msvs P = (30,000 kg )(-25 m/s) + (10,000 kg )(0 m/s) P = -750,000 (kg)( m/s) v = P/m v = -750,000 (kg)( m/s) / (30,000 kg ) + (10,000 kg ) v = 18.75 m/s W
22. Working the Problem The Westbound train, after the initial impact with the stationary transit collides with the Eastbound train also after its initial impact with one of the stationary transits. Calculate the velocity after the crash between the two trains if they stuck together.
23. Calculate the velocity after the crash between the two trains Net Momentum before = Net Momentum after Known Want Pw = 750,000 (kg)( m/s) Pnet before Pe = -800,000 (kg)( m/s) v after Pnet = Pe- Pw Pnet = 800,000 (kg)( m/s) - 750,000 (kg)( m/s) Pnet = 50,000 (kg)( m/s) v = P/m v = 50,000 (kg)( m/s) / (40,000 kg ) + (50,000 kg ) v = .56 m/s E
24. Stating the Problem The Battalac, which has a mass of 1500 kg is occupied by batfink, 50 kg, and Karate, 150kg and is traveling at 50 m/s when it is forced off the road anddown a 50 meter embankment.
25. Working the Problem Calculate the vertical velocity of the Battalac just before it strikes the ground.
26. Find the vfy Known Want mB = 1,500 kg v vohB = 50 m/s mb = 50 kg mk = 150 kg vf2 = vo2 + 2a∆y vf2 = 0 m/s + 2(-9.8 m/s2)(50m) v = -31.3 m/s
27. Working the Problem Calculate the magnitude of the velocity of the Battalac at impact with the ground.
28. Calculate the magnitude of the velocity of the Battalac y 50 m/s 31.3 m/s x a2 + b2 = c2 502 + 31.32 = 58.99 m/s or TAN -1= 31.3/50 = 32.05* Vf = Vx/COS 32.05* = -58.99 m/s or Vf = Vy/SIN 32.05* = -58.98 m/s
29. Working the Problem Calculate the momentum of the Battalac at the moment of first impact with the ground.
30. The momentum of the Battalac at impact with the ground. Known Want mB = 1,500 kg P vfB = 58.99 m/s mb = 50 kg mk = 150 kg P = mv P = (1700 kg)(-58.99 m/s) P = -100,283 (kg m/s)
