ConcepTest 3.4a Firing Balls I A small cart is rolling at constant

Transcript ConcepTest 3.4a Firing Balls I A small cart is rolling at constant

UNIT 2 Two Dimensional Motion And Vectors

ConcepTest 3.4a

Firing Balls I

A small cart is rolling at constant velocity on a flat 1) it depends on how fast the cart is moving track. It fires a ball straight 2) it falls behind the cart up into the air as it moves. 3) it falls in front of the cart After it is fired, what happens 4) it falls right back into the cart to the ball?

5) it remains at rest

ConcepTest 3.4a

Firing Balls I

5) it remains at rest In the frame of reference of the cart, the ball only has a vertical component of velocity. So it goes up and comes back down. To a ground observer, both the cart and the ball have the

same horizontal velocity

, so the ball still returns into the cart.

when viewed from train when viewed from ground

Thursday/Friday September 22-23

Projectiles: Zero Launch Angle

TODAY’S AGENDA

Thursday, September 22    Projectile Motion Mini-Lesson: Zero Launch Angle  Problem Quiz 1 Vectors Hw: Complete Practice C Problems (all)

UPCOMING…

    Fri: More Zero Launch Angle Mon: Projectile Motion @ any angle Tues: Wed: LAB 3: Projectile Motion Problem Quiz 2 Projectile Motion

Projectile Motion

Something is fired, thrown, shot, or hurled near the earth’s surface. 6

One Dimensional Projectile

Two Dimensional Projectile

Horizontal Component of Velocity

Vertical Component of Velocity

Horizontal and Vertical Motion

Perpendicular components of motion are independent of each other.

Launch Angle

Zero Launch Angle

V o

Sample Problem 1) The Zambezi River flows over Victoria Falls in Africa. The falls are approximately 108m high. If the river is following horizontally at 3.60 m/s just before going over the falls, what is the final velocity of the water when it hits the bottom? Assume the water is in freefall as it drops.

Find the final vertical velocity Find the time of flight 𝒚 = 𝒗 𝒐 𝒕 − 𝟏 𝟐 𝒈𝒕 𝟐 𝒚 = − 𝟏 𝟐 𝒈𝒕 𝟐 𝒗 𝒗 𝒇𝒚 𝒇𝒚 = 𝒗 𝒊𝒚 = −𝒈𝒕 − 𝒈𝒕 −𝟏𝟎𝟖 𝒎 = −(𝟒. 𝟗𝟏)𝒕 𝒕 = 𝟒. 𝟔𝟗 𝐬 𝟐 𝒗 𝒇𝒚 = (−𝟗. 𝟖𝟏)(𝟒. 𝟔𝟗𝒔) 𝒗 𝒇𝒚 = −𝟒𝟔. 𝟎 𝒎 𝒔 17

1) continued… Find the time of flight Find the final vertical velocity Ө Final horizontal velocity 𝒕 = 𝟒. 𝟔𝟗 𝐬 𝒗 𝒇𝒚 𝒗 𝒇𝒙 𝒎 = −𝟒𝟔. 𝟎 𝒎 𝒔 = 𝟑. 𝟔𝟎 𝒔 𝒗 𝒇 = 𝟑. 𝟎𝟔 𝟐 + (−𝟒𝟔. 𝟎 𝟐 ) 𝒗 𝒇 = −𝟒𝟔. 𝟏 𝒎 𝒔 𝜽 = −𝟖𝟓. 𝟓° 𝜽 = tan −𝟏 −𝟒𝟔. 𝟎 𝟑. 𝟔𝟎 𝒗 𝒇 = −𝟒𝟔. 𝟏 𝒎 𝒔 @ 𝟖𝟓. 𝟓° 𝒃𝒆𝒍𝒐𝒘 𝒕𝒉𝒆 (−𝒙) 𝒂𝒙𝒊𝒔 18

Sample Problem 2) 19

3) Sample Problem 20

Sample Problem 4) A lunch pail is accidently kicked off a steel beam on a building under construction. Suppose the initial horizontal speed is 1.50 m/s. a ) How far does the lunch pail fall after it travels 3.50 m horizontally? 21

Sample Problem 4) A lunch pail is accidently kicked off a steel beam on a building under construction. Suppose the initial horizontal speed is 1.50 m/s. b ) If the building is 2.50 x 10 2 m tall, and the lunch pail is knocked off the top floor, what will be the horizontal displacement of the lunch pail when it reaches the ground? 22

Sample Problem 4) A lunch pail is accidently kicked off a steel beam on a building under construction. Suppose the initial horizontal speed is 1.50 m/s. c ) If the building is 2.50 x 10 it reaches the ground? 2 m tall, and the lunch pail is knocked off the top floor, what is the final velocity the lunch pail when 23

Sample Problem 5) The LZ N07 is a newly designed airship in the manner of the old Zeppelin airships built in Germany between 1908 and 1940. This airship can travel with a horizontal speed of 1.30 x 10 2 km/h. If a parcel is dropped from this airship, so that it lands 135 m in front of the spot over which it was released, how far above the ground is the airship?

Sample Problem 6) A squirrel on a limb near the top of the tree loses its grip on a nut, so that the nut slips away horizontally at a speed of 10.0 cm/s. If the nut lands at a horizontal distance of 18.6 cm, how high above the ground is the squirrel?

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