Projectile Motion: 2D Free Fall!

Learning Target

Today I am applying constant velocity and constant acceleration to the motion of objects flying through the air. I know I have it when I separate projection motion into two separate motions.

1. What would happen on planet NARANG if a sphere was launched at an angle into the vacuum?

2. What would happen if you launched a sphere at an angle into the air on the Moon?

3. What would happen if you launched a sphere at an angle into the atmosphere on Jupiter?

4. What force acts on an object in the air here on Earth?

5. What is the direction of that force/acceleration? What does this tell me about the horizontal motion?

6. Why is the path a parabola and not a triangle like boats and airplanes?

Horizontal Motion (x-axis) Vertical Motion (y-axis)Acceleration magnitude?

Velocity at the top?

Equations that apply?

Be able to identify if an object is in projectile motion.

Know why vertical and horizontal motions are independent for projectile motion.

Predict what projectile motion would look like on different planets.

Be able to justify what sphere would strike first, go the fastest and

7. A stee7. A sphere is launched horizontally with a speed v from the top edge of a table of height h above a level floor. At the same instant, another steel sphere is dropped from the edge of the same table.

a. Which sphere strikes the floor first? i. The sphere launched horizontally

ii. The sphere droppediii. The spheres land at the same time

Explain Result:

b. What is the horizontal motion of the fired sphere? Why?

c. Model a sphere thrown horizontally. Sketch the path of a sphere and draw arrows showing its horizontal and vertical velocity at three points along the path. Vary the length of your arrows to show the magnitude of the velocities.

d. Which sphere is traveling faster when it hits the ground? Why?

e. Does the mass of the spheres matter? Why or why not?

Know if a sphere is fired horizontally and dropped simultaneously which will strike the ground first

What do objects in projectile motion have in common?

8. How could you find the instantaneous velocity at any point in the motion if you know the horizontal velocity magnitude and the vertical velocity magnitude at that instant?

Learning targetToday I am applying constant acceleration and constant velocity to projectile motion. I know I have it when I only use parallel vectors in any equation.

9. Alice throws a sphere horizontally off a 20 meter cliff with a horizontal speed of 10.0 m/s.

a. What is the time in the air?Horizontal vertical

b. What is the velocity just before it hits the ground (this includes direction)?

c. What is the horizontal displacement?

10. What if we could launch a horizontal projectile so fast that the Earth curved away as it fell towards the Earth? What’s that called?

a. Why are astronauts weightless?

11. A projectile is launched at an angle from level ground. i. Horizontal velocity

ii. Vertical velocityiii. Horizontal accelerationiv. Vertical accelerationv. Angle at which the projectile is launched

a. Which of the above choices is NOT constant throughout the flight of the projectile?

b. Which of the above choices is zero throughout the flight of the projectile?

c. Which of the above choices changes direction during the flight of the projectile?

12.

13. A battleship simultaneously fires two shells at enemy ships. If the shells follow the parabolic trajectories shown, which ship gets hit first?

vx=5 m/svy=29.4 m/s

a=____t=0

vx=____vy=____

a=____t=6 s

vx=____vy=____

a=____t=5 s

vx=____vy=____

a=____t=1 s

vx=____vy=____

a=____t=4s

vx=____vy=____

a=____t=2 s

vx=____vy=____

a=____t=3 s

Identify the acceleration at any point in projectile

Be able to label horizontal/vertical velocities at any given time.

AB

What does the time for projectile motion depend on?

14. Arlo kicks a football with a velocity of 12.8 m/s at an angle of 38 degrees with the horizontal.

a. What is the time that the football is in the air?X Y

b. What is the football’s displacement in the horizontal direction?

c. What is the maximum height that the football will reach?

d. What is the total velocity just before the ball hits the ground?

Solve a projectile motion problem (object dropped, object given an initial horizontal velocity, object given initial velocity at an angle) for

Horizontal velocity

Vertical velocity at any given time or displacement

Time in air

Horizontal displacement

Height of highest point

(total) Velocity before striking the ground

Angle of (total) velocity before striking the ground

15. A projectile is fired with initial velocity vo at an angle 0 with the horizontal and follows the trajectory shown above. Which of the following pairs of graphs best represents the vertical components of the velocity and acceleration. v and a, respectively, of the projectile as functions of time t?

16. What would the graphs look like for the horizontal components of the velocity and acceleration as a function of time?

17. A daredevil decides to jump a canyon. Its walls are equally high and 10 m apart. He takes off by driving a motorcycle up a short ramp sloped at an angle of 15 degrees. What minimum speed must he have in order to clear the canyon?

X Y

Draw velocity vs time graphs of a motion