Unit 1 Motion. Projectile Motion

Transcription

1 Unit 1 Motion Projectile Motion

2 Motion to Date Uniform Motion Accelerated Motion Relative Motion

3 Uniform Motion Motion with a constant velocity - Constant speed - Same direction Equation: v d t

4 Problems 1. An airplane travels 300 km in 1.25 hours. Find its speed.

5 2. A hunter travels 3 km [N] in 0.75 h and 2 km [E] in 30 minutes. Find her average: A) speed

6 B) velocity

7 3. A kayaker can travel at 4 m/s relative to the water. If she is in a river that has a current of 2 m/s [S] find her velocity with respect to (wrt) the (i) shore and (ii) water if she heads A) Upstream B) Downstream C) Directly across the stream

8 Applet Glenbrook VECTOR REVIEW?? Vector Addition Suppose the river is 50 m wide. How far will the kayak land downstream on the other side?

9 4. Suppose the kayaker wants to land directly across the stream. A) Find the angle she would have to point to do so. B) Find the time it would take for her to get to the other side.

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11 Accelerated motion Motion with changing velocity Examples? Accelerated motion occurs when either the speed is changing speeding up or slowing down Direction is changing Curved motion

12 Equations for accelerated motion Page 56 text Formula Sheet

13 Examples 1. A cyclist can accelerate from 10. km/h to 30. km/h in 3.5s. Find his acceleration.

14 2. A glove is dropped from a chairlift and hits the ground 2 seconds later. A) How high is the chairlift?

15 B) How fast was the glove travelling when it hit the ground?

16 3. Police measure skid marks to determine the speed of a car just before skidding started. If the acceleration of car is 7.5 m/s 2 (based on the surface condition of the road) and the length of the skid is 45 m, determine the speed the car was traveling before locking the tires. (Assuming the car was stopped at the end of the skid.)

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18 100 m 4. Determine the speed the object hits the ground. The object has an initial upwards velocity of 25 m/s.

19 5. Determine the time it would take a rock to hit the ground if: A) it was dropped from a height of 2 m. B) thrown upwards at 20 m/s from the 2 m height. C) thrown downwards at 20 m/s from the 2 m height.

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21 Page 74 #54, 55, 65, 66

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23 What is projectile motion? Anything that is thrown that has some horizontal motion. Jumping on a bike, skis, snowboards, skidoos, skakeboards, wakeboards, horses, etc. Running off a diving board. Arrows, or bullets that are shot. Throwing footballs or basketballs, or kicking a soccer ball.

24 A projectile is any object which, once projected, continues its motion by its own inertia and is influenced only by the downward force of gravity.

25 It is important to study this if you want objects to land in certain spots Movie

26 What describes the path of a projectile? Parabola In 3204 projectile motion is limited to negligible air resistance /projectile-motion

27 Horizontal motion (x-direction) is uniform motion (no acceleration) Vertical motion (y-direction) is uniform acceleration (-9.8 m/s 2 ) Distance travelled in the x-direction is defined as range. Time is the same in both the x and y direction. Truck and ball

28 Equations for Projectile Motion Horizontal Motion (x-direction) Uniform Motion d x x v t R v t Range x Vertical Motion (y-direction) Accelerated Motion 1 2 dy v1yt at ad v v 2 y 2 y 1 y v v a t v2y v1 dy 2 2y 1y y t

29 Components of Velocity Mathematically determine the components of velocity at certain points along a projectile s motion. Applet

30 Find the Components of Velocity of the cannon ball for each of the first five seconds Note: Launch angle is 0 o and initial velocity is 20 m/s Find the velocity at each second

31 Types of Projectile Motion Horizontal motion moving off a cliff (No vertical motion initially) Projected motion at an angle q, and lands at a point

32 Projected motion at an angle q, and lands at a point: A) level with launch B) Above launch C) below launch

33 Projectiles with zero vertical velocity Worksheet 1 Glenbrook applet for answers

34 Projectiles with NON zero vertical Worksheet 2 velocity

35 Worksheet 3

36 Assignment

37 The Physics of Juggling

38 Applet Air resistance

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45 Page #54. 2 d at t 2d a t 2(553 m) 9.80 m/ s 2 The time is 10.6 s.

46 #55. 1 d vt 1 at 2 2

47 #65.

48 #66. Back

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