Presentation is loading. Please wait.

Presentation is loading. Please wait.

the science of collision

Similar presentations


Presentation on theme: "the science of collision"— Presentation transcript:

1 the science of collision
MOMENTUM the science of collision

2 = “Keep Goingness” of an object.
p = mv where p = momentum m = mass in kg v = velocity in m/s Momentum

3 They can stop dead. i.e. mv = mv So if a fast moving little object collides with a slow moving big object head on

4

5

6

7 Example: What is the momentum of a 300 g swallow going 15 m/s?
p = mv = (.300 kg)(15 m/s) p = 4.5 kgm/s Duh! I can tell by the mass.

8 What is the momentum of a 0.25 kg swallow going 5.2 m/s ?
1.3 kgm/s p = mv p = (.25 kg )(5.2 m/s) = 1.3 kgm/s W

9 What velocity must a 275 gram bullet have for its momentum to be 126
What velocity must a 275 gram bullet have for its momentum to be kg-m/s? 460. m/s p = mv 126.5 kgm/s = (.275kg)v v = (126.5 kgm/s)/(.275kg) = 460 m/s W

10 A bowling ball has a momentum of 43
A bowling ball has a momentum of 43.6 kg-m/s when it is moving at 12 m/s. What is its mass? 3.6 kg p = mv 43.6 kgm/s = m(12 m/s) m = (43.6 kgm/s)/ (12 m/s) = 3.6 kg W

11 LAW OF CONSERVATION OF MOMENTUM
The sum of the momentum before and after the collision remains the same. m1v1 = m2 v2

12 Elastic and inelastic collisions in one dimension
Momentum is conserved in any collision, elastic and inelastic. Mechanical Energy is only conserved in elastic collisions. Perfectly inelastic collision: After colliding, particles stick together. There is a loss of energy (deformation). Elastic collision: Particles bounce off each other without loss of energy. Inelastic collision: Particles collide with some loss of energy, but don’t stick together.

13 Perfectly inelastic collision of two particles
(Particles stick together) Notice that p and v are vectors and, thus have a direction (+/-) There is a loss in energy Eloss

14 Elastic collision of two particles
(Particles bounce off each other without loss of energy. Momentum is conserved: Energy is conserved:

15 The momenta must be equal but opposite:
60 kg Fran is running at 4 m/s when she collides with 80 kg Joe. They hit and stop dead, so how fast was Joe going? 3 m/s The momenta must be equal but opposite: Fran: p=mv=(60 kg)(4 m/s)=240 kgm/s Joe: p=mv, 240 kgm/s = (80 kg)v, v = (240 kgm/s)/ (80 kg) = 3 m/s. W

16 Consider the previous problem:
Since momentum is really a vector, the true initial momenta were: Fran: p=mv=(60 kg)(+4 m/s)=+240 kgm/s Joe: p=mv=(80 kg)(-3 m/s)=-240 kgm/s The total momentum was the same before and after the collision. This is true for every collision. This is very useful

17


Download ppt "the science of collision"

Similar presentations


Ads by Google