ACCELERATION AND FREE FALL CHAPTER 3 ACCELERATION ACCELERATION

• Slides: 25

ACCELERATION AND FREE FALL CHAPTER 3

ACCELERATION •

ACCELERATION • When velocity and acceleration are in the same direction, the speed of the object increases with time. • When velocity and acceleration are in opposite directions, the speed of the object decreases with time.

ACCELERATION • 4. 0 s vf=-10. 0 m/s vi=-2. 0 m/s

ACCELERATION • 4. 0 s vf=-2. 0 m/s vi=-10. 0 m/s

DECELERATION VS. NEGATIVE ACCELERATION • Deceleration – Reduction in speed • Negative Acceleration – Acceleration vector is in the negative-x direction

INSTANTANEOUS ACCELERATION •

MOTION DIAGRAMS

ONE-DIMENSIONAL MOTION WITH CONSTANT ACCELERATION • Many applications of mechanics involve objects moving with constant acceleration • Constant Acceleration • Instantaneous acceleration = average acceleration

COMPARING MOTION GRAPHS

VELOCITY AS A FUNCTION OF TIME •

REALITY CHECK •

DISPLACEMENT AS A FUNCTION OF TIME • The area under the line on a velocity vs. time graph is equal to the displacement of the object.

AN AUTOMOBILE MANUFACTURER CLAIMS THAT ITS SUPERDELUXE SPORTS CAR WILL ACCELERATE UNIFORMLY FROM REST TO A SPEED OF 38. 9 M/S IN 8. 00 S. •

VELOCITY AS A FUNCTION OF DISPLACEMENT •

EQUATIONS FOR MOTION IN A STRAIGHT LINE UNDER CONSTANT ACCELERATION Equation Information Given by Equation Velocity as a function of time Displacement as a function of time Velocity as a function of displacement

IN COMING TO A STOP, A CAR LEAVES SKID MARKS 92. 0 M LONG ON THE HIGHWAY. ASSUMING A DECELERATION OF 7. 00 M/S 2, ESTIMATE THE SPEED OF THE CAR JUST BEFORE BRAKING. •

FREE FALL • When air resistance is ignored, all objects in free fall near the Earth’s surface fall at the same constant acceleration. • Galileo • Dropped objects of different weights of Leaning Tower of Pisa • Or did he? • Inclined Planes • Diluting Gravity

FREE FALL •

FREE FALL • A tennis player on serve tosses a ball straight up. While the ball is in free fall , does the acceleration • • • A. Increase B. Decrease C. Increase then Decrease D. Decrease then Increase E. Remain Constant

FREE FALL • A tennis player on serve tosses a ball straight up. While the ball is in free fall , does the acceleration • • • A. Increase B. Decrease C. Increase then Decrease D. Decrease then Increase E. Remain Constant

FREE FALL • As the tennis ball in the previous question travels through the air, its speed • • • A. Increases B. Decreases C. Decreases then Increases D. Increases then Decreases E. Remains the Same

FREE FALL • As the tennis ball in the previous question travels through the air, its speed • • • A. Increases B. Decreases C. Decreases then Increases D. Increases then Decreases E. Remains the Same

A BASEBALL IS HIT NEARLY STRAIGHT UP INTO THE AIR WITH A SPEED OF 22 M/S. •