{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

PHY183-Lecture23 - Physics for Scientists Engineers 1...

Info icon This preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
February 24, 2006 Physics for Scientists&Engineers 1 1 Physics for Scientists & Physics for Scientists & Engineers 1 Engineers 1 Spring Semester 2006 Lecture 23
Image of page 1

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

View Full Document Right Arrow Icon
February 24, 2006 Physics for Scientists&Engineers 1 2 Momentum Review Momentum Review Linear Momentum Newton’s 2 nd Law Impulse Average Force r p = m r v r F = d r p dt r J ! r Fdt t i t f " r J = ! r p r J = r F av ! t
Image of page 2
February 24, 2006 Physics for Scientists&Engineers 1 3 Impulse and Car Safety Devices Impulse and Car Safety Devices Car collision: very large impulse (cannot be changed) Typical collision time is very short Since , this means a very large force acting on the driver All passive safety devices (seat belt, air bag, crash crumple zones) are designed to extend time interval and thus to reduce average force r F av = r J ! t
Image of page 3

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

View Full Document Right Arrow Icon
February 24, 2006 Physics for Scientists&Engineers 1 4 Impulse and Sports Impulse and Sports Why can one hit for more power with less tension on the tennis racket strings? Answer: relationship between impulse, force, and time If average force is fixed, increasing the contact time between racket and ball increases impulse given to ball r J = r F av ! t
Image of page 4
February 24, 2006 Physics for Scientists&Engineers 1 5 Quiz 22.1 Quiz 22.1 • Jack swings at a 0.2 kg ball that is moving west with a velocity of 40 m/s and hits a line drive. The ball leaves his bat with a velocity of 40 m/s due east. Assuming the ball is in contact with the bat for 0.010 s, what is the average force of the bat on the ball? a) 800 N East b) 1600 N East c) 1600 N West d) 800 N West
Image of page 5

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

View Full Document Right Arrow Icon
February 24, 2006 Physics for Scientists&Engineers 1 6 Quiz 22.1 Quiz 22.1 • Jack swings at a 0.2 kg ball that is moving west with a velocity of 40 m/s and hits a line drive. The ball leaves his bat with a velocity of 40 m/s due east. Assuming the ball is in contact with the bat for 0.010 s, what is the average force of the bat on the ball? a) 800 N East b) 1600 N East c) 1600 N West d) 800 N West 0.2 (40 ( 40) / ) 16 kg m/s east 16 1600 N east .01 p kg m s p F t ! = " " = ! = = = !
Image of page 6
February 24, 2006 Physics for Scientists&Engineers 1 7 Collisions Collisions Collisions of two (or more) objects, or one object with a “wall” Two cars in a traffic accidents Two billiard balls One billiard ball bouncing off the wall Asteroid hitting Earth Two air molecules bouncing off each other Question : If we know the momenta of the two objects before the collision, can we predict the momenta after the collision?
Image of page 7

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

View Full Document Right Arrow Icon
February 24, 2006 Physics for Scientists&Engineers 1 8 Momentum Conservation in Collisions Momentum Conservation in Collisions During the collision object 1 exerts a force on object 2.
Image of page 8
Image of page 9
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