9 momentum and its conservation - weebly

9 Momentum and Its Conservation2 Conservation of Momentum

REVIEW VOCABULARY

momentum

NEW VOCABULARY

closed system

isolated system

law of conservation of

momentum

law of conservation of

angular momentum

MAINIDEAWrite the Main Idea for this section.

Recall and write the definition of the Review Vocabulary term.

momentum

Use your book to define each term.

closed system

isolated system

law of conservation of momentum

law of conservation of angular momentum

Science Notebook • Momentum and Its Conservation 142

Program: TX HS Science Component: PPP SCI NTBKPRINTER PDF

Vendor: LASERWORDS Grade: N/A

135_148_PPP_SN_C09_666028.indd 142135_148_PPP_SN_C09_666028.indd 142 06/05/13 3:15 PM06/05/13 3:15 PM

Copyright © M

cGraw

-Hill Education. Perm

ission is granted to reproduce for classroom use.

2 Conservation of Momentum (continued)

Summarize information about the collision of two balls.

GET IT? Explain the difference between a closed system and an isolated system.

TRY IT !

See the next page for a problem about momentum.

Draw an example of recoil. On the lines below, explain your example.

Student Edition, pp. 244–247





Copy

righ

t © M

cGra

w-H

ill E

duca

tion.

Per

mis

sion

is g

rant

ed to

repr

oduc

e fo

r cla

ssro

om u

se.

TRY IT !Problem

Railroad car A, with mass 6275 kg, is traveling east at 6.5 m/s along a straight track. It strikes Railroad car B, with mass 5155 kg, which is also traveling east along the same track at 3.8 m/s. The two railroad cars stick together. Assume the track is frictionless. How fast do the two attached railroad cars move immediately after the collision?

1. ANALYZE AND SKETCH THE PROBLEM

KNOWNS UNKNOWNS

mA = mB = = ?

vAi = vBi =

2. SOLVE FOR THE UNKNOWNS

Define the system:

Write pi = pf in terms of the cars' masses and velocities.

Rewrite this equation in terms of the velocity, vf , after the collision.

Solve the equation for vf.

3. EVALUATE THE ANSWER

• Is the magnitude realistic?


Student Edition, p. 246

Use with Example Problem 3.

Use this column for

scratch work and

sketches.





Copyright © M

cGraw




Summarize the process in which a rocket in space changes velocity using rocket fuel.

Describe features of two-dimensional collisions by filling in the missing terms.

The law of conservation of holds for all

systems with no forces. In order for a system to be isolated,

you have to ignore . When a moving object strikes a stationary

object, the moving object's initial momentum equals the of the

final momentums of the objects. The sum of the components of the

momentum before and after the collision must also be equal.

TRY IT !

See the next page for a problem about a two-dimensional collision.

Compare and contrast linear momentum and angular momentum by completing the diagram.

Linearmomentum

Angularmomentum

Is equal to . . .

mv

Is conserved is the systemexperiences no . . .

force

Law of Conservation

pi = pf






Copy

righ

t © M

cGra

w-H

ill E

duca

tion.

Per

mis

sion

is g

rant

ed to

repr

oduc

e fo

r cla

ssro

om u

se.


Student Edition, p. 250

Use with Example Problem 5.

Use this column for

scratch work and

sketches.

TRY IT !Problem

A 1445-kg car, C, moving east at 21.2 m/s, collides with a 2625-kg car, D, moving south at 17.5 m/s, and the cars stick together. In what direction and with what speed do they move after the collision?

1. ANALYZE AND SKETCH THE PROBLEM

KNOWNS UNKNOWNS

mc = vCi,x = = ?

mD = vDi,y = = ?

2. SOLVE FOR THE UNKNOWNS

Determine the magnitudes of the initial momenta of the cars.

Set up equations for pf,x and pf,y.

Determine the final momentum, pf.

Solve for θ.

Determine the final speed.





Copyright © M

cGraw





TRY IT ! (continued)

3. EVALUATE THE ANSWER

• Does the angle's sign make sense?

GET IT? Analyze Why does Earth precess as it rotates?

SUMMARIZE

How does the MAINIDEA for this section relate to the chapter’s BIGIDEA?

REVIEW IT !

30. MAINIDEA The outer rim of a plastic disk is thick and heavy. Besides making it easier to catch, how does this affect the rotational properties of the plastic disk?

31. Speed A cart, weighing 24.5 N, is released from rest on a 1.00-m ramp, inclined at an angle of 30.0° as shown in Figure 16. The cart rolls down the incline and strikes a second cart weighing 36.8 N.

a. Define the two carts as the system. Calculate the speed of the first cart at the bottom of the incline.

b. If the two carts stick together, with what initial speed will they move along?30.0°

1.00 m

24.5 N

36.8 N

Figure 16





Copy

righ

t © M

cGra

w-H

ill E

duca

tion.

Per

mis

sion

is g

rant

ed to

repr

oduc

e fo

r cla

ssro

om u

se.

32. Conservation of Momentum During a tennis serve, the racket of a tennis player continues forward after it hits the ball. Is momentum conserved in the collision between the tennis racket and the ball? Explain, making sure you define the system.

33. Momentum A pole-vaulter runs toward the launch point with horizontal momentum. Where does the vertical momentum come from as the athlete vaults over the crossbar?

34. Initial Momentum During a soccer game, two players come from opposite directions and collide when trying to head the ball. The players come to rest in midair and fall to the ground. Describe their initial momentums.

34. Critical Thinking You catch a heavy ball while you are standing on a skateboard, and then you roll backward. If you were standing on the ground, however, you would be able to avoid moving while catching the ball.

a. Identify the system you use in each case.

b. Explain both situations using the law of conservation of momentum.






Copyright © M

cGraw



9 momentum and its conservation - weebly

Documents