1 / 17

Warm-up

10/15 p. 5. Warm-up. 1. Sketch a prediction of a velocity vs. time graph for a freely falling object if you ignore air resistance.

sukey
Download Presentation

Warm-up

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. 10/15 p. 5 Warm-up 1. Sketch a prediction of a velocity vs. time graph for a freely falling object if you ignore air resistance. 2. You left the cafeteria running initially at 2.7 m/s and accelerated uniformly at a rate of 0.02 m/s2 until you arrived at classroom 3.5 minutes (210 seconds) later. How fast were you running when you arrived to class? Use WTF, circle answer & include units Velocity (m/s) Time (s)

  2. What do these graphs indicate? Speed Time Distance vs. Time Speed vs. Time Speed vs. Time Speed Time

  3. Describing Motion • There are five things we need to know about an object’s motion in order to fully describe it. • v = velocity (initial vs. final) • t = time • d= displacement (vs. distance) • a = acceleration • As long as you know at least 3 of the 4 variables, you can solve for the 4th & the 5th. • These only work in situations where acceleration is constant.

  4. Kinematic Equations*KNOW how to manipulate* • * NO “t” • * NO “Vf” • Vf= Vi + at * NO “d” • Vf2= Vi2 + 2ad * NO “t”

  5. Practice Problems An airplane accelerates down a runway at 3.20 m/s2 for 32.8 s until is finally lifts off the ground. Determine the distance traveled before takeoff. WTF

  6. Feather & Hammer Drop on the Moon http://www.youtube.com/watch?v=5C5_dOEyAfk

  7. A feather is dropped on the moon and hits the surface of the moon 1.29 seconds later. The acceleration of gravity on the moon is 1.67 m/s2. Determine the height the feather was dropped.

  8. A car starts from rest and accelerates uniformly to a speed of 26.0 m/s for a distance of 110 m. Determine the acceleration of the car.

  9. What happens when you drop something? • Gravity pulls the object downward and causes it to accelerate. • The acceleration of gravity is constant: 10 m/s2 • The acceleration of gravity is always downward and constant. • We will always use -10 m/s2

  10. Consider an object thrown straight up • It continues to move upward for a while, then it comes back down. • At the highest point, when the object is changing its direction of motion from upward to downward, its instantaneous speed is zero. • It then starts downward, just as if it had been dropped from rest at that height.

  11. vi(up ) = vf(down) • vf(up) = vi(down ) = 0 • The change in speed each second is the same whether the object is going upward or downward.

  12. Look at one side or the other

  13. Hint • If you are trying to find time up, solve for time down. • If you are trying to find distance up, solve for distance down.

  14. Practice Problems  1. Henrietta is walking through a dark room when she sees a scary animal. She jumps up at a speed of 3.4 m/s. How high does she jump? WTF

  15. Practice Problems 2. Jerry the tomcat wants to jump up onto the refrigerator to reach the cheesy-poofs. If the refrigerator is 2m tall, how fast must Jerry jump to make it?

  16. Practice Problems 3. A bullet is fired straight up with a muzzle velocity of 460 m/s. What is the maximum height the bullet will reach?

  17. Closure Create a up/down motion problem, show your WTF, solve & explain to your neighbor

More Related