1 / 10

Aim: How can we explain the motion of elevators using Newton’s 2 nd law?

Aim: How can we explain the motion of elevators using Newton’s 2 nd law?. F = 150 N. Do Now: What is the acceleration of this object?. m = 20 kg. F Net = ma 150 N – 100 N = (20 kg)a 50 = 20a 2.5 m/s 2 up = a. F = 100 N. Elevator Problems. F N = Normal Force (scale reading).

vaughan-johns
Download Presentation

Aim: How can we explain the motion of elevators using Newton’s 2 nd law?

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. Aim: How can we explain the motion of elevators using Newton’s 2nd law? F = 150 N Do Now: What is the acceleration of this object? m = 20 kg FNet = ma 150 N – 100 N = (20 kg)a 50 = 20a 2.5 m/s2 up = a F = 100 N

  2. Elevator Problems FN = Normal Force (scale reading) A man is standing on a scale while in an elevator What forces exist? Fg = Weight = mg

  3. While the elevator is at rest Objects at rest: FNet = 0 Forces are balanced Fg = FN While the elevator is moving with a constant velocity Objects moving with a constant velocity: FNet = 0 Forces are balanced Fg = FN

  4. A 50 kg man is standing on a scale in an elevator while it is at rest. How much does he weigh? Fg = mg Fg = (50 kg)(9.8 m/s2) Fg = 490 N What does the scale read? FNet = 0 FN = Fg FN = 490 N

  5. The elevator now accelerates up at 2 m/s2 What does the scale read? FNet = ma The object will always accelerate in the direction of the larger force FN is larger FN – Fg = ma FN – 490 N = (50 kg)(2 m/s2) FN – 490 = 100 FN = 590 N FN = ? I feel heavier!!! This is your apparent weight Fg = 490 N

  6. The elevator now accelerates down at 1 m/s2 What does the scale read? FNet = ma The object will always accelerate in the direction of the larger force Fg is larger FN - Fg = ma FN - 490 N = -(50 kg)(1 m/s2) FN - 490 N = -50 N FN = 440 N FN = ? I feel lighter!!! Fg = 490 N

  7. The elevator now moves with a constant velocity of 3 m/s up. What does the scale read? FN = ? I feel normal!!! FNet = 0 FN = Fg FN = 490 N Fg = 490 N

  8. The elevator now is in free fall. What does the scale read? FNet = ma The object will always accelerate in the direction of the larger force Fg is larger Fg – FN = ma 490 N – FN = (50 kg)(9.8 m/s2) 490 – FN = 490 FN = 0 N FN = ? The person seems weightless Fg = 490 N

  9. Spinning in Zero Gravity

  10. What is the acceleration of the elevator? FNet = ma The object will always accelerate in the direction of the larger force FN is larger FN – Fg = ma 980 N – 630 N = ma 350 = 64.3a a = 5.4 m/s2 up FN = 980 N Fg = mg 630 N = m(9.8 m/s2) m = 64.3 kg Fg = 630 N

More Related