Mon 10/22 and Thurs 10/25
LP 15: Projectile Motion – Sink the Bismarck!
Objectives:
- I can measure the velocity of a marble shooter.
- I can find the initial angle θ to hit a target given v and Δx.
- I can sink the Bismarck!
Agenda:
- The Situation10
- HMS King George V example10
- Sink the Bismarck! Lab70
Homework:
Example. The Royal Navy battleship HMS King George V is engaged in battle with the Kriegsmarine (German Navy) battleship Bismarck. King George V has 10 14 in guns that fire a shell with a velocity of 730 m/s. The Bismarck is 12 miles (19308 meters) away. The Bismarck’s deck is at the same height as the King George V’s guns. What angle should the King George V shoot at to hit the Bismarck?
HorizontalVertical
Displacement:∆x ∆y
Velocity vxvyi
vyf
Acceleration ay
Time t t
Name ______Date ______Block _____
Sink the Bismarck!
The HMS Hood, pride of the Royal Navy, has been sunk by the Nazis and their new battleship Bismarck. Prime Minister Churchill has called for the immediate destruction of the Bismark to avenge the Hood and make the Atlantic Ocean safe for the American convoys supplying our war effort.
You are fire control officers on one of His Majesty’s warships. It is your job to aim your ship’s guns. Before you can join the fight against Bismarck, you must calibrate your gun by measuring how fast it shoots.
Marble Shooter Number:______Marble Diameter:______cm = ______m
1) Loosen the nut on the back of the marble shooter, adjust the marble shooter to 20°, then tighten to nut again.
2) Attach the Photo-gate to the wooden block in front of the barrel and set up the timer.
3) Do not point the marble shooter at people or objects (yet)!
4) Pull the marble shooter back to the 4th notch.
5) Load the marble into the barrel.
6) Reset the timer as you may have tripped it loading the marble.
7) Have a team member place their hand in front on the Photo-gate to stop the marble from flying off. Don’t lose your marble!
8) Push down on the pin from the back (if you push from the top or front your finger could slow it down) to fire the marble.
9) Record the time from the timer.
10) Repeat 4 more times.
11) Find the average time.
12) Find the average velocity of your marble shooter using the diameter as Δd.
Time (s) / t1 / t2 / t3 / t4 / t5 / tavg / vavg (m/s)Admiral Tovey has ordered every ship under his command to engage the Bismarck. Using your rangefinders (meter sticks) you’ve determined that the Bismarck is
______meters away. Determine the inclination (angle) required for your shots to hit the Bismarck.
HorizontalVertical
Displacement:∆x ∆y
Velocity vxvyi
vyf
Acceleration ay
Time t t
You have 5 shots to hit the Bismarck. If you miss your 1st shot, check your math. If your math was correct and you missed, it should have been a near miss. Try changing θ a few degrees to shoot a little further or closer. Once you hit, fire for effect!
Range (m) / Inclination (degrees) / Hit? (Yes/No)Challenge: You know how to solve for the angle θ when Δy = 0. Work in your group to come up with a way to solve for θ when Δy ≠ 0. You have access to a graphing calculator. Show your strategy to Mr. Kalb for even more chocolate.