Download presentation

Presentation is loading. Please wait.

Published byCamilla Morris Modified over 2 years ago

1
Impulse Contents: Impulse/WB Area Under Force Graph Ft = mv Rocket Science Rocket Demos

2
Change in momentum = Impulse Impulse = F t where F = Force t = time that the force is exerted (F or t = 0???) Example: What impulse is imparted by exerting a 12 N force for 4.0 s? 1.Impulse = F t = (12 N)(4.0 s) 2.Impulse = 48 Ns

3
Whiteboards Impulse 11 | 22

4
What is the impulse of a 6.12 N force acting for 2.3 seconds? 14 Ns Impulse = F t Impulse = ( 6.12 N )( 2.3 s)=14 Ns W

5
A rocket engine is rated at 14 Ns of impulse, and burns for 1.7 seconds. What is the thrust of the engine? 8.2 N Impulse = F t 14 Ns = F(1.7 s) F = (14 Ns)/ (1.7 s) = 8.24 = 8.2 N W

6
Impulse is area under = (40 N)(6.0s) = 240 Ns t F 100 N 5.0 s Example - Impulse is area under F vs t graph

7
Whiteboards 11 | 2 | 323

8
Average F = 70 N, t = 8.0 s, Impulse = (70 N)(8.0 s) = 560 Ns What is the impulse? W 560 Ns t F 100 N 5.0 s

9
Impulse = (40 N)(3.0 s) + (70 N)(5.0 s)= 470 Ns What is the impulse? W 470 Ns t F 100 N 5.0 s

10
Impulse = (10. N)(1.73 s-0.11 s) + (28 N-10 N)(0.42 - 0.21) = 19.98 Ns (about 20 Ns) What is the impulse of the D12 engine? W 20 Ns

11
Impulse = F t = m v F = Force (N) t = Elapsed time (s) m = Mass (kg) v = Change in velocity (m/s) Force, time, mass, and velocity Example: A pitcher pitches a 0.145 kg baseball at 40. m/s, and the batter hits it directly back at 50. m/s to the outfield. What is the average force exerted by the bat if the collision lasted.013 s? 1.F t = m v 2.(F )(.013 s) = (0.145 kg)(-90 m/s) 3.F = (0.145 kg)(-90 m/s)/(.013 s) 4.F = -1003.8 N ≈ -1.0x10 3 N (units/sign)

12
Whiteboards Ft = mv 11 | 2 | 323

13
What force for 10. seconds makes a 2.0 kg rocket speed up to 75 m/s from rest? 15 N (m)( v) = (F )( t) (2.0 kg)(75 m/s) = (F )(10 s) F = (2.0 kg)(75 m/s)/(10 s) = 15 N

14
A baseball bat exerts a force of 200. N on a.50 kg ball for.10 seconds. What is the ball’s change in velocity? 40. m/s (m)( v) = (F )( t) (.50 kg)( v) = (200. N )(.10 s) v = (200. N )(.10 s)/(.50 kg) = 40. m/s

15
Jolene exerts a 50. N force for 3.0 seconds on a stage set. It speeds up from rest to.25 m/s. What is the mass of the set? 6.0 x 10 2 kg (m)( v) = (F )( t) (m)(.25 m/s) = (50. N )(3.0 s) m = (50. N )(3.0 s)/(.25 m/s) = 600 kg = 6.0 x 10 2 kg

16
One last thing: Deriving Newton’s second law: m v = F t Finally: F = m v = ma = p t t

17
Rocket Propulsion FtFt = mvmv So: F = engine thrust t = time to burn fuel m = mass of fuel burned v = exhaust gas velocity

18
Rocket Propulsion Example 1: A rocket burns fuel at a rate of 1.2 kg/s, with an exhaust velocity of 1250 m/s. What thrust does it develop? F t = m v v = 1250 m/s m = 1.2 kg t = 1 s (F)(1 s) = (1.2 kg)(1250 m/s), F = 1500 N

19
Rocket Propulsion Example 2: A model rocket engine develops 12 N of thrust with an exhaust velocity of 718 m/s. What is its fuel burn rate? F t = m v F = 12 N v = 718 m/s m = ? kg t = 1 s (12 N)(1 s) = m(718 m/s), m =.0167 kg Burn rate =.0167 kg/s

20
Whiteboards 11 | 2 | 323

21
A certain rocket engine burns.0352 kg of fuel per second with an exhaust velocity of 725 m/s. What thrust does it generate? 25.5 N F t = m v F(1 s) = (.0352 kg)(725 m/s), F = 25.5 N W

22
The Saturn V’s first stage engines generated 33.82 MN of thrust ( 33.82 x 10 6 N ) with an exhaust velocity of 2254.7 m/s. What was its fuel burn rate? 15,000 kg/s F t = m v (33.82 x 10 6 N)(1 s) = m(2254.7 m/s), m = 15,000 kg Burn Rate = 15,000 kg/s W

23
A D12 engine generates 11.80 N of thrust burning fuel at a rate of.0143 kg/s. What is the exhaust velocity? 825.2 m/s F t = m v (11.80 N)(1 s) = (.0143 kg) v, v = = 825.2 m/s W

24
Which Rocket Accelerates faster? A B Demo – F14

27
Rocket Propulsion © Microsoft Encarta Solid Fuel Engine:

28
Rocket Propulsion © Microsoft Encarta Solid Fuel Engine: Thrust of the Engine: F = m v t Big v means big F Big v also means lots of pressure Danger Will Robinson!

29
© Estes

30
Lookout! m =.5 kg, F t = 20 Ns F t = m v 20 Ns =.5kg v v = ? (x 2.237 for mph) © Estes

31
Rocket Propulsion © Microsoft Encarta Liquid Fuel Engine: How do you keep it from tipping? Why the “steam” coming off?

32
Saturn V Animation (Flash in IE) Saturn V Rocket - Apollo missions First stageSecond stageThird stageL.E.MCommand Module Escape Tower

33
http://xkcd.com/1133/http://xkcd.com/1133/ - Up goer 5 – explanation using most common 1000 words Also many good YouTube videos of launch

34
Ion Propulsion systems Low thrust/high Δv 20-50 km/s exhaust velocity Dawn

35
Gridded Xenon ion drive (Like Dawn has) where’s the power come from?

36
The Dawn spacecraft has a mass of about 770 kg, and an ion drive with an exhaust velocity of 35,000 m/s that generates about 92 millinewtons of thrust. (.092 N) How what is the “burn” rate for this engine? Ft = mv (.092 N)(1.0 s) = m(35,000 m/s) m = 2.62857E-06 kg/s How big a change in velocity can 50 kg of fuel give the spacecraft? The final mass will be 770 – 50 = 720 kg, on the average the spacecraft will have a mass of 745 kg So the delta v is approximately: (745 kg)(Δv) = (50 kg)(35,000 m/s) Δv ≈ 2350 m/s

Similar presentations

OK

Impulse A change in momentum. How to change momentum Any object that has momentum is going to be hard to stop To stop an object a force needs to be applied.

Impulse A change in momentum. How to change momentum Any object that has momentum is going to be hard to stop To stop an object a force needs to be applied.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on fire alarm system Jit ppt on manufacturing process Ppt on natural disaster flood Ppt on asian continent deserts Ppt on multiplication for class 2 Ppt on views in dbms definition Ppt on our country india Ppt on condition monitoring definition Ppt on natural and artificial satellites around earth Ppt on types of houses in india