2. How do most vehicles propel themselves? Tire pushes on ground, ground pushes on tire… Normal Forces and Friction

3. How do most vehicles propel themselves? Plane pushes on air, air pushes on plane.

4. Rockets have nothing to push off of…

5. Which physics principles are related to rockets?

6. Newton’s 1 st Law Newton’s 2 nd Law

7. Which physics principles are related to rockets? Newton’s 3rd Law Conservation of Momentum

8. Blast-off…

9. Rocket Propulsion Mass of rocket Mass of fuel Velocity at time t Increase in rocket velocity after mass has been ejected Velocity of fuel relative to the rocket. (Quantity is velocity of ejected mass with respect to motionless frame.)

10. Rocket Propulsion For blast-off, velocity at time t is zero:

11. Rocket Propulsion For the limit as Δt approaches zero: As ejected mass increases, rocket mass decreases:

12. Rocket Propulsion Integrate!

13. Rocket Propulsion

15. Thrust Thrust is the force exerted on a rocket by exhausted gases.

16. A Rocket in Space: 1.A rocket moving in free space has a speed of 3x10 3 m/s relative to Earth. Its engines are turned on, and fuel is ejected at a speed of 5x10 3 m/s relative to the rocket a)What is the speed of the rocket relative to Earth once its mass is reduced to one half its mass before ignition? b)What is the thrust on the rocket if it burns the fuel at a rate of 50kg/s?

17. A Rocket in Space: 1.A rocket moving in free space has a speed of 3x10 3 m/s relative to Earth. Its engines are turned on, and fuel is ejected at a speed of 5x10 3 m/s relative to the rocket a)What is the speed of the rocket relative to Earth once its mass is reduced to one half its mass before ignition?

18. A Rocket in Space: 1.A rocket moving in free space has a speed of 3x10 3 m/s relative to Earth. Its engines are turned on, and fuel is ejected at a speed of 5x10 3 m/s relative to the rocket b)What is the thrust on the rocket if it burns the fuel at a rate of 50kg/s?