Mechanics Unit Notes #3: Free Fall and Projectile Notes Falling Objects 1. What forces act on falling objects? 2. Does freefall only apply to objects moving downward? 3. What’s the acceleration due to the gravitational force on Earth? 4. Acceleration equation: Formula Circle Symbols Units 5. What are the possible motions for an object accelerating? 6. A ball is thrown vertically upward. While the ball is in free fall does its acceleration increase, decrease or remain constant? 7. A sky diver steps from a high flying helicopter. If there were no air resistance, how fast would she be falling at the end of a 12 second jump?
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Mechanics Unit Notes #3: Free Fall and Projectile Notes
Falling Objects1. What forces act on falling objects?
2. Does freefall only apply to objects moving downward?
3. What’s the acceleration due to the gravitational force on Earth?
4. Acceleration equation: Formula Circle Symbols Units
5. What are the possible motions for an object accelerating?
6. A ball is thrown vertically upward. While the ball is in free fall does its acceleration increase, decrease or remain constant?
7. A sky diver steps from a high flying helicopter. If there were no air resistance, how fast would she be falling at the end of a 12 second jump?a. given b. Formula
c. fill it in d. answer with units
8. How fast is a ball falling 1s after it is dropped?
Mechanics Unit Notes #3: Free Fall and Projectile Notes
a. 5 m/sb. 9.8 m/sc. 15 m/sd. 19.6 m/se. 29.4 m/s
9. How fast is a ball falling 2 s after it is dropped?a. 5 m/sb. 9.8 m/sc. 15 m/sd. 19.6 m/se. 29.4 m/s
10. A ball is thrown vertically upward with a speed of 30 m/s. How much time does it take the ball to reach the top of its path?
a. 1 sb. 2 sc. 3 sd. 4 se. 5 s
11. Alice throws a ball into the air. Fill in the blanks
12. Graph the velocity of the ball as a function of time.
t=1sa= -9.8m/s2v=19.6 m/s t=5s a=___ v=_____
a=___t=2s t=4sa=___v=_____ v=_____
a=___t=3s t=3sa=___v=_____ v=_____
What is the slope of this graph?
What physics word?
Mechanics Unit Notes #3: Free Fall and Projectile Notes
13. If you were on the moon (so no air resistance) and dropped a hammer and a feather from the same elevation at the same time, would they strike the surface of the moon at the same instant?
14. A person standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, which ball strikes the ground with a greater speed? The one initially thrown_____
a. upwardb. downwardc. neither-the both hit at the same speed
15. You are throwing a ball straight up in the air. At the highest point, the ball’s a. Velocity and acceleration are zerob. Velocity is not zero but its acceleration is zeroc. Acceleration is not zero, but its velocity is zerod. Velocity and acceleration are both not zero
16. What does terminal velocity mean?
17. How does a sky diver change their terminal velocity
18. Displacement for an accelerating object equation.( This assumes initial velocity of zero!) Formula Circle Symbols Units
Mechanics Unit Notes #3: Free Fall and Projectile Notes
19. A rock dropped from the top of a cliff picks up speed as it falls. Pretend that a speedometer and odometer are attached to the rock to show readings of speed and distance at 1 second intervals. Both speed and distance are zero at time zero. Note that after falling 1 second the seed reading is 9.8 m/s and the distance fallen is 5 m. a. The readings for succeeding seconds of fall are not shown and are left for you to complete. So draw the position of the speedometer pointer and write in the correct odometer reading for each time. Neglect air resistance.
b. The speedometer reading increases by the same amount
______m/s, each second. This increase in speed per second is
called ____________.
c. The distance fallen increases as the square of the ___________
d. If it takes 7 seconds to reach the ground then its speed at impact
is ________ m/s, the total distance fallen is _________m, and its
acceleration of fall just before impact is ________m/s2.
20. Calculate the vertical distance an object dropped from rest would cover in 12 seconds if it fell freely without air resistance.
Be able to justify what sphere would strike first, go the fastest and
Mechanics Unit Notes #3: Free Fall and Projectile Notes
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 force acts on an object in the air? What is the direction of that force?
2. 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?
Know if a sphere is fired horizontally and dropped simultaneously which will strike the ground first
Mechanics Unit Notes #3: Free Fall and Projectile Notes
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?
3. What would happen on planet NARANG if a sphere was launched at an angle into the vacuum?
4. What would happen if you launched a sphere at an angle into the air on the Moon?
5. What would happen if you launched a sphere at an angle into the atmosphere on Jupiter?
6. Why is the path a parabola?
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.
Mechanics Unit Notes #3: Free Fall and Projectile Notes
Horizontal Motion (x-axis) Vertical Motion (y-axis)Acceleration magnitude?
Velocity at the top?
Equations that apply?
Mechanics Unit Notes #3: Free Fall and Projectile Notes
7. Alice throws a sphere horizontally off a 20 meter cliff with a horizontal speed of 10m/s.
a. What is the time in the air?Horizontal vertical
b. What is the horizontal displacement?
8. 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?
9. A projectile is launched at an angle from level ground. i. Horizontal velocity
Mechanics Unit Notes #3: Free Fall and Projectile Notes
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?
10.
11. 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?
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