Lecture18%20Friction%20and%20Drag%20Forces-handout

Lecture18%20Friction%20and%20Drag%20Forces-handout - Today...

Info icon This preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Today Newton’s 3 rd Law continued Friction and air drag
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Newton’s Third Law Weight and normal force are not an action/reaction pair. Action/reaction partners have same type, act on two different objects. Two surfaces in contact exert a normal force on each other. Reaction partner to weight of the TV is the gravitational attraction of Earth by the TV. Weight and normal force, same magnitude here. Why not consider the normal force the reaction partner to the weight, since the weight causes the normal force. Because they are not always equal in magnitude and opposite in direction: w n
Image of page 2
W12 Q3 A 1200 kg car pushes a 2800 kg truck that has a dead battery. When the driver steps on the accelerator, the drive wheels of the car push against the ground with a force of 1500 N. What is the magnitude of the force of the truck on the car? Hint: Identify the forces and the correct action/reaction pair.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Solution The blue arrows show the correct action/reaction pair: Force of the car on the truck (F ConT ) and the Force of the truck on the car (F TonC ). The force exerted by the ground on the car F GonC is shown in red . We know it’s 1500 N. For the car, 2 nd law yields: F GonC – F TonC = m C a For the truck we obtain: F ConT = m T a Substitute for acceleration a and solve for F TonC (Ans.: 1050 N)
Image of page 4
Tension Forces A student is pulling on a rope that is fixed to a tree. His force is 100 N. 1) What is the tension in the rope? 2) What is the force of the tree on the rope? A. 0 N B. 100 N C. 200 N D. More than 200 N
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Tension Forces Two students are pulling on a rope. Each students pulls with a force of 100 N.
Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern