Lecture09

# Lecture09 - PHYSICS 149 Lecture 9 Chapter 3 3.2 Velocity...

This preview shows pages 1–10. Sign up to view the full content.

PHYSICS 149: Lecture 9 • Chapter 3 – 3.2 Velocity and Acceleration – 3.3 Newton’s Second Law of Motion – 3.4 Applying Newton’s Second Law – 3.5 Relative Velocity Lecture 9 Purdue University, Physics 149 1

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

View Full Document
Lecture 9 Purdue University, Physics 149 2 t x(t) Δ t Δ x x(t) t Velocity (m/s) • The average velocity is the change in position (vector) divided by the change in time. • Instantaneous velocity is the limit of average velocity as t gets small. It is the slope of the x(t) plot.
Lecture 9 Purdue University, Physics 149 3 If the average velocity of a car during a trip along a straight road is positive, is it possible for the instantaneous velocity at some time during the trip to be negative? A - Yes B - No correct If the car is traveling in a straight path the velocity will always be positive. The car needs to travel in the opposite direction to get a negative velocity . The car might have reversed for a little while along the trip creating a negative instantaneous velocity at the point. If the overall displacement of the car is positive for that particular time interval, than the average velocity is positive as well. ILQ 1

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

View Full Document
Lecture 9 Purdue University, Physics 149 4 How to determine x from v(t) • The total displacement x during and time t is the area under the graph v(t) • Assume 1D, and v constant: t v Δ x v 1x t 1 t 2
Lecture 9 Purdue University, Physics 149 5 • The average acceleration is the change in velocity divided by the change in time. • Instantaneous acceleration is limit of average acceleration as t gets small. It is the slope of the v(t) plot. t v(t) Δ t Δ v v(t) t Acceleration (m/s 2 )

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

View Full Document
Average Acceleration • Average acceleration is the change in velocity during the time interval during which the velocity changed. • The x- and y-components of the average velocity are: • Typical units for the magnitude of acceleration are m/s 2 , km/s 2 , and so on. Lecture 9 6 Purdue University, Physics 149
Instantaneous Acceleration • Instantaneous acceleration is the average acceleration we measure when the time interval is infinitesimally short. • The x- and y-components of the instantaneous velocity are: Lecture 9 7 Purdue University, Physics 149

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

View Full Document
Direction of Acceleration • If speed is increasing , v and a are in same direction. • If speed is decreasing , v and a are in opposite direction. Lecture 9 8 Purdue University, Physics 149
• A go-kart travels around a circular track at a constant speed. Which of these is a true statement? (a) The go-kart has a constant velocity. (b) The go-kart has zero acceleration.

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 35

Lecture09 - PHYSICS 149 Lecture 9 Chapter 3 3.2 Velocity...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online