Physics QuickyPhysics Quicky

A Stone Thrown A Stone Thrown DownwardDownward

A boy on a bridge throws a stone A boy on a bridge throws a stone vertically downward with an initial vertically downward with an initial velocity of 14.7 m/s toward the river velocity of 14.7 m/s toward the river below. below.

If the stone hits the water 2.00 s later, If the stone hits the water 2.00 s later, what is the height of the bridge above what is the height of the bridge above the water?the water?

Kinematic PracticeKinematic Practice

PhysicsPhysics

September 16, 2008September 16, 2008

1. How far does a bicyclist 1. How far does a bicyclist travel, if he has been riding travel, if he has been riding for 20 seconds at 4 m/s?for 20 seconds at 4 m/s?

2. If a car travels 240 meters 2. If a car travels 240 meters in 60 seconds, what was its in 60 seconds, what was its

average speed?average speed?

3. A car traveling initially at 3. A car traveling initially at 12 m/s accelerates at 5 m/s12 m/s accelerates at 5 m/s22 for 8 seconds. What is its for 8 seconds. What is its

new velocity?new velocity?

4. How much time does it 4. How much time does it take an eagle to travel 420 take an eagle to travel 420 meters, moving at a rate of meters, moving at a rate of

6 m/s? 6 m/s?

5. An object initially moving 5. An object initially moving with a velocity of 5 m/s is with a velocity of 5 m/s is speeds up at a rate of 6 speeds up at a rate of 6 m/sm/s22 for 2 s. What is the for 2 s. What is the total distance traveled? total distance traveled?

6. A racecar with an initial 6. A racecar with an initial velocity of 20 m/s velocity of 20 m/s

decelerates at a rate of 2 decelerates at a rate of 2 m/sm/s22 for 4 seconds. What is for 4 seconds. What is

its new velocity? its new velocity?

7. A racecar with an initial 7. A racecar with an initial velocity of 20 m/s velocity of 20 m/s

decelerates at a rate of 2 decelerates at a rate of 2 m/sm/s22 for 4 seconds. How far for 4 seconds. How far

has it traveled? has it traveled?

8. A car initially moving at 12 8. A car initially moving at 12 m/s increases its velocity to m/s increases its velocity to 36 m/s in 6 seconds. What 36 m/s in 6 seconds. What is the car’s acceleration?is the car’s acceleration?

9. A student drops an apple 9. A student drops an apple from a building 20 meters from a building 20 meters

high. How long does it take high. How long does it take to hit the ground?to hit the ground?

10. How far does a train with 10. How far does a train with an initial velocity of 45 m/s an initial velocity of 45 m/s travel when accelerating at travel when accelerating at

4 m/s4 m/s22 for 10 s? for 10 s?

11. A car traveling at 8 m/s 11. A car traveling at 8 m/s accelerates at 2 m/saccelerates at 2 m/s22 for 3 for 3 seconds. What is its new seconds. What is its new

velocity?velocity?

12. A horse traveling with a 12. A horse traveling with a velocity of 20 m/s velocity of 20 m/s

decelerates at 5 m/sdecelerates at 5 m/s22 until it until it comes to a rest.comes to a rest.

How far did it travel ?How far did it travel ?

13. A ball is thrown upward 13. A ball is thrown upward with an initial velocity of 30 with an initial velocity of 30 m/s. Where is the ball after m/s. Where is the ball after

4 seconds?4 seconds?

14. A boat moving at a 14. A boat moving at a speed of 6 m/s accelerates speed of 6 m/s accelerates at 3 m/sat 3 m/s22. How fast will the . How fast will the car be moving after it has car be moving after it has

accelerated for 45 m?accelerated for 45 m?

15. A ball is rolling with an 15. A ball is rolling with an initial velocity of 24 m/s and initial velocity of 24 m/s and slows to a velocity of 4 m/s slows to a velocity of 4 m/s in 5 seconds. What is its in 5 seconds. What is its

acceleration?acceleration?

16. How long does it take a 16. How long does it take a car to accelerate from 2 m/s car to accelerate from 2 m/s

to 10 m/s with an to 10 m/s with an acceleration of 4 m/sacceleration of 4 m/s22? ?

17. A moving car slows 17. A moving car slows down at 3 m/sdown at 3 m/s22 for 4 for 4

seconds until it reaches a seconds until it reaches a stop. What was its initial stop. What was its initial

velocity?velocity?

18. A ball is thrown downward 18. A ball is thrown downward at an initial velocity of 6 m/s at an initial velocity of 6 m/s from a bridge. How far does from a bridge. How far does

the stone travel in 3 seconds? the stone travel in 3 seconds?

19. How long does it take a 19. How long does it take a car to slow down from 45 car to slow down from 45

m/s to 25 m/s decelerating m/s to 25 m/s decelerating at 5 m/sat 5 m/s22? ?

20. A car traveling initially at 8 m/s 20. A car traveling initially at 8 m/s accelerates at a rate of 4 m/saccelerates at a rate of 4 m/s22 for 2 s. for 2 s.

What is the car’s velocity at that time?What is the car’s velocity at that time?

The car then blows a tire, slows and The car then blows a tire, slows and comes to a halt, decelerating at 8 m/scomes to a halt, decelerating at 8 m/s22. . How long did it take to stop? How long did it take to stop?

* A ball is thrown from a height of 25.0 m above the * A ball is thrown from a height of 25.0 m above the ground with an initial horizontal velocity of 8.25 ground with an initial horizontal velocity of 8.25

m/s.m/s.

(a)(a) How long is the ball in flight before striking the How long is the ball in flight before striking the ground?ground?

(b)(b) How far from the building does the ball strike the How far from the building does the ball strike the ground?ground?

Next Lecture: Next Lecture: PROJECTILE (2-D) MOTION.PROJECTILE (2-D) MOTION.

Physics Homework 9/17Physics Homework 9/17

Read Chapter 2 Conceptual Physics (Hewitt)Read Chapter 2 Conceptual Physics (Hewitt)

Do Problems 22, 23, 26, 27, 30, 33, Do Problems 22, 23, 26, 27, 30, 33,

41, 43, 44, 4841, 43, 44, 48

DO RIGHT NOW…DO RIGHT NOW…

In Wilson Chapter 2 (37, 41, 63, 87,107)In Wilson Chapter 2 (37, 41, 63, 87,107)