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Summary

  • The approach to two-dimensional collisions is to choose a convenient coordinate system and break the motion into components along perpendicular axes.
  • Momentum is conserved in both directions simultaneously and independently.
  • The Pythagorean theorem gives the magnitude of the momentum vector using the x - and y -components, calculated using conservation of momentum in each direction.

Conceptual questions

Momentum for a system can be conserved in one direction while not being conserved in another. What is the angle between the directions? Give an example.

The angle between the directions must be 90°. Any system that has zero net external force in one direction and nonzero net external force in a perpendicular direction will satisfy these conditions.

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Problems

A 1.80-kg falcon is diving at 28.0 m/s at a downward angle of 35 ° . It catches a 0.650-kg dove from behind in midair. What is their combined velocity after impact if the dove’s initial velocity was 7.00 m/s directed horizontally? Note that v ^ 1, i is a unit vector pointing in the direction in which the hawk is initially flying.

A hawk is flying toward a dove. The hawk is moving in a direction that is 35 degrees down from the horizontal at v 1 i = 28.0 meters per second v 1 i hat. The dove is moving to the right at 7.00 meters per second i hat.
(credit “hawk”: modification of work by “USFWS Mountain-Prairie”/Flickr; credit “dove”: modification of work by Jacob Spinks)

22.1 m/s at 32.2 ° below the horizontal

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A billiard ball, labeled 1, moving horizontally strikes another billiard ball, labeled 2, at rest. Before impact, ball 1 was moving at a speed of 3.00 m/s, and after impact it is moving at 0.50 m/s at 50° from the original direction. If the two balls have equal masses of 300 g, what is the velocity of the ball 2 after the impact?

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A projectile of mass 2.0 kg is fired in the air at an angle of 40.0 ° to the horizon at a speed of 50.0 m/s. At the highest point in its flight, the projectile breaks into three parts of mass 1.0 kg, 0.7 kg, and 0.3 kg. The 1.0-kg part falls straight down after breakup with an initial speed of 10.0 m/s, the 0.7-kg part moves in the original forward direction, and the 0.3-kg part goes straight up.

A bullet at launch has v sub i = 50.0 meters per second directed at 40 degrees above the horizontal. At peak before explosion, the bullet is directed to the right with vector v sub i, x = v sub i x x hat. At leak after explosion, there are three pieces. M 1 = 1.0 k g has v 1 f = minus 10 meters per second j hat, downward. M 2 = 0.7 k g has vector v sub 2, f = v sub 2 f i hat to the right. M 3 = 0.3 k g has vector v sub 3, f = v sub 3 f j hat up..
  1. Find the speeds of the 0.3-kg and 0.7-kg pieces immediately after the break-up.
  2. How high from the break-up point does the 0.3-kg piece go before coming to rest?
  3. Where does the 0.7-kg piece land relative to where it was fired from?

a. 33 m/s and 110 m/s; b. 57 m; c. 480 m

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Two asteroids collide and stick together. The first asteroid has mass of 15 × 10 3 kg and is initially moving at 770 m/s. The second asteroid has mass of 20 × 10 3 kg and is moving at 1020 m/s. Their initial velocities made an angle of 20° with respect to each other. What is the final speed and direction with respect to the velocity of the first asteroid?

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A 200-kg rocket in deep space moves with a velocity of ( 121 m/s ) i ^ + ( 38.0 m/s ) j ^ . Suddenly, it explodes into three pieces, with the first (78 kg) moving at ( 321 m/s ) i ^ + ( 228 m/s ) j ^ and the second (56 kg) moving at ( 16.0 m/s ) i ^ ( 88.0 m/s ) j ^ . Find the velocity of the third piece.

( 732 m/s ) i ^ + ( −80.6 m/s ) j ^

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A proton traveling at 3.0 × 10 6 m/s scatters elastically from an initially stationary alpha particle and is deflected at an angle of 85° with respect to its initial velocity. Given that the alpha particle has four times the mass of the proton, what percent of its initial kinetic energy does the proton retain after the collision?

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Three 70-kg deer are standing on a flat 200-kg rock that is on an ice-covered pond. A gunshot goes off and the dear scatter, with deer A running at ( 15 m/s ) i ^ + ( 5.0 m/s ) j ^ , deer B running at ( −12 m/s ) i ^ + ( 8.0 m/s ) j ^ , and deer C running at ( 1.2 m/s ) i ^ ( 18.0 m/s ) j ^ . What is the velocity of the rock on which they were standing?

( 0.21 m/s ) i ^ + ( 0.25 m/s ) j ^

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A family is skating. The father (75 kg) skates at 8.2 m/s and collides and sticks to the mother (50 kg), who was initially moving at 3.3 m/s and at 45° with respect to the father’s velocity. The pair then collides with their daughter (30 kg), who was stationary, and the three slide off together. What is their final velocity?

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An oxygen atom (mass 16 u) moving at 733 m/s at 15.0° with respect to the i ^ direction collides and sticks to an oxygen molecule (mass 32 u) moving at 528 m/s at 128° with respect to the i ^ direction. The two stick together to form ozone. What is the final velocity of the ozone molecule?

341 m/s at 86.8° with respect to the i ^ axis.

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Two cars approach an extremely icy four-way perpendicular intersection. Car A travels northward at 30 m/s and car B is travelling eastward. They collide and stick together, traveling at 28° north of east. What was the initial velocity of car B?

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Questions & Answers

What are the factors that affect demand for a commodity
Florence Reply
differentiate between demand and supply giving examples
Lambiv Reply
differentiated between demand and supply using examples
Lambiv
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appreciation
Eliyee
explain perfect market
Lindiwe Reply
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
Ezea
What is ceteris paribus?
Shukri Reply
other things being equal
AI-Robot
When MP₁ becomes negative, TP start to decline. Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 • Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 • Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Kelo
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Shukri
Can I ask you other question?
Shukri
what is monopoly mean?
Habtamu Reply
What is different between quantity demand and demand?
Shukri Reply
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
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what is the difference between economic growth and development
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Economic growth as an increase in the production and consumption of goods and services within an economy.but Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
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any question about economics?
Awais Reply
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
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In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50. A,Calculate quantities of x and y which maximize utility. B,Calculate value of Lagrange multiplier. C,Calculate quantities of X and Y consumed with a given price. D,alculate optimum level of output .
Feyisa Reply
Answer
Feyisa
c
Jabir
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
Gsbwnw Reply
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product
Abdureman
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Source:  OpenStax, University physics volume 1. OpenStax CNX. Sep 19, 2016 Download for free at http://cnx.org/content/col12031/1.5
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