Center of mass and momentum Questions and Answers

H O L X hrw8c9p5 A cubical box open at the top with edge length 68 cm is constructed from metal plate of uniform density and negligible thickness see the figure Find the z co the center of mass of the box cm

Course Contents HW Bonus center of mass of the Earth Moon nrw8c9p115 How far is the center of mass of the Earth Moon system from the center of the Earth m Appendix C gives the masses of the Earth and the Moon and the dist etween the two Submit Answer Tries 0 8 xpress thes previous answer as a fraction of the Earth s radius

E4 123 5 6 7 8 9 10 time s A 4 kg block sliding on a frictionless surface is moving with an initial velocity of 7 m s An impulse is applied to the block as shown on the graph What is the block s speed at time t 10 s

A spring loaded ballistic cart measuring 0 5 kg is in contact with a second 0 8 kg cart The carts are initially at rest on a level surface The spring is released and the lighter cart is observed to move at 0 4 m s afterward What is the velocity of the other cart

Consider a projectile 0 1 kg fired into a ballistic pendulum 0 5 kg the resulting collision is Elastic Inelastic none of the above

A billiard ball moving at 2 5 m s strikes a stationary ball of the same mass After the collision the first ball moves at 2 17 m s at an angle of 30 0 with respect to the original line of motion Assuming an elastic collision and ignoring friction and rotational motion find the struck ball s velocity speed and direction after the collision Speed after collision Direction after collision Choose Choose

45 4 0 m s 3 0 m s 2 0 m s 20 g 30 g 12 3 Problem 3 The figure above on the left shows a collision between three balls of clay The three balls hit simultaneously and stick together What are the speed and direction of the resulting blob of clay Answer 0 85 m sec and 72 2 below the r axis Problem 4 Speed deamplifier In the figure above on the right block 1 of mass m slides along an 1 axis on a frictionless floor at speed 4 m sec Then it undergoes a one dimensional elastic collision with stationary block 2 of mass m 2m Next block 2 undergoes a one dimensional elastic collision with stationary block 3 of mass m3 4m What then is the speed of block 3 Answer m sec or 1 78 m sec 16

In the figure a weightlifter s barbell consists of two identical uniform spherical masses each with radius 0 140 m and mass of 40 0 kg The weights are connected by a 0 900 m uniform steel rod with a mass of 8 00 kg Find the moment of inertia of the barbell about the axis through the center see figure Hint 2 108 0 90m Axis O 1 Moment of inertia of a sphere about an axis passing through the center Icenter 2 Moment of inertia of a rod about an axis passing through its center Irod Icenter mr 3 Parallel axis theorem IParallel Instruction please input the numerical value accurate to three significant figures without the unit MR R is the radius of the sphere ML L is the Length of the rod

A small comet moves at velocity 5100 m s Heat from the sun makes it break into two smaller pieces The first piece has mass 1310 kg and velocity 5640 m s in the same direction as before The second piece has mass 2380 kg What is its velocity m s magnitude direction Select

The image below is of your new best friend m 56kg on a skateboard negligible mass At first they are not moving Say you toss a basketball m 0 5kg to your new best friend with a speed of 15m s As a reminder ofst p mv momentum mass x velocity 1 Calculate the momentum of the basketball in the air 5 pts

Describe what will occur when your new best friend catches the basketball explaining your thinking You don t need to include math in this answer 5 pts

1 3 0 m s 1 kg Before Collision 2 kg After Collision 1 kg 2 kg A block of mass 1 kg slides on a frictionless horizontal surface with a velocity of 3 0 m s to the right as shown above and collides with a block of mass 2 kg that is at rest As a result of the collision the 1 kg block comes to rest Which of the following correctly states whether the collision is elastic or inelastic and provides a valid justification A Elastic because the total momentum before the collision equals the total momentum after B Elastic because some of the initial kinetic energy is converted to other forms of energy but the total energy i conserved C Inelastic because the total momentum before the collision does not equal the total momentum after

65 II A figure skater can increase her spin rotation rate from an initial rate of 1 0 rev every 1 5 s to a final rate of 2 5 rev s If her initial moment of inertia was 4 6 kg m what is her final moment of inertia How does she physically accomplish this change

torque platform A friend starts him rotating with an initial rotational speed as shown on the left part of the figure When the man pulls the heavy masses in close to his axis of rotation as shown on the right part of the figure his rotational speed increases by a factor of two In order to conserve his rotational momentum for the right part of the figure his rotational inertia must have 2015 Pon Education Inc 3 3 a decreased to one half of the initial value on the left b decreased to one third the initial value on the left c remained the same d increased to double the initial value on the left e increased to three times the initial value on the left

8 A 50 0 kg woman riding on a 10 kg cart is moving east at 5 0 m s The woman jumps off the front of the cart and lands on the ground at 7 0 m s eastward What is the final velocity of the cart Before After Object 1 Mass Velocity Momentum Object 2 Mass Velocity Momentum

What is the approximate mass of the boy 15 kg 20 kg 40 kg 10 kg 30 kg

6 When should you apply the conservation of momentum equation

3 What is the equation that relates impulse to momentum

An astronaut at rest in space with mass 84 kg fires a thruster that expels 35 g of hot gas at 875 m s What is the velocity of the astronaut after firing the thruster

A 4 0 kg model rocket is launched shooting 50 0 g of burned fuel from its exhaust at an average velocity of 625 m s What is the velocity of the rocket after the fuel has burned

A 9 00 kg mass is moving to the right with a velocity of 14 0 m s A 12 0 kg mass is moving to the left with a velocity of 5 00 m s Assuming that these two balls have a head on collision and stick together what will be the final velocity of the combination

Suppose that you have a mass of 45 7 kg and are standing on frictionless roller skates Someone then throws you a 2 50 kg mass with a velocity of 14 5 m s and you catch it What will be your resultant velocity

A 6813 kg truck traveling at 4 79 m s east collides with a 1908 kg car moving at 24 05 m s in a direction 44 south of west After the collision the two vehicles remain tangled together With what velocity magnitude only does the wreckage begin to move Round your answer to 2 decimal places

The diagram depicts a 2 kg mass colliding with and sticking into a second box What is the mass of the second box 6 Before collision 2 kg After collision 4 m 2 kg

A bowling ball has a mass of 5 1 kg and is traveling with a velocity of 22 m s down the lane How much momentum does it have Do not round

9 A 45 0 kg ice skater stands at rest on the ice A friend tosses the skater a 5 0 kg ball The skater and the ball then move backwards across the ice with a speed of 0 5 m s What was the speed of the ball at the moment just before the skater caught it 5 m s

A 6 kg object starts at rest It is th A How much initial momentum P c m x v 6 X Calculate the impulse that act R

2 A 3 kg bird is flying at 18 m s above a lake looking for food The bird spots a 1 2 kg fish at rest in the water After the bird picks the fish up out of the water what is the bird and the fish s new velocity Before After Object 1 Mass Velocity Momentum Object 2 Mass Velocity Momentum

4 A 55 kg softball player is running holding a 0 15 kg softball at a speed of 2 4 m s east She throws the ball with a speed of 28 m s east What is her immediate new velocity after the throw Before Object 1 Mass Velocity Momentum Object 2 Mass Velocity 6 Momentum 7

5 An 1850 kg luxury sedan stopped at a traffic light is struck from the rear by a compact car with a mass of 975 kg The two cars become entangled as a result of the collision If the compact car was moving at a velocity of 22 m s to the north before the collision what is the velocity of the entangled mass after the collision Object 1 Object 2 Before After Mass Velocity Momentum Mass Velocity Momentum

10 Two astronauts of masses 60 They suddenly push each other

4 cart of mass M 500 kg and initial speed 5 00 m s collides head on with a second cart of nass M 3 00kg at rest Assuming the collision is elastic find the speed of M after the collision that

A pole is planted into the ground at a 38⁰ angle. At the end of the pole is a 500 N pot. What force would need to be added to the pole in the Y-direction to maintain mechanical equilibrium?

What is the moment of inertia of a uniform solid cylinder about its central axis of diameter d = 0.190 m, and total mass M = 1.65 kg? Show your work.

Two train cars are coupled together, traveling together on a straight level track with a velocity of 1.50 m/s to the right. The leading Car A has a mass of 5,000 kg, while the trailing Car Bhas a mass of 12,000 kg. (Assume 3 significant figures on all masses.) A small explosion suddenly separates the two cars. Afterward, Car A has a velocity of 2.50 m/s to the right. Ignore all external friction on the train cars. What is the net impulse received by Car A, in kg-m/s? ________ kg-m/s Enter a POSITIVE value for rightward, or NEGATIVE value for leftward.

On a frictionless horizontal floor, two objects collide. Object A, which is moving in a velocity of 72 m/s, is 7 times of object B, which has a velocity of 40 m/s. Object A moves to the right while object B moves to the left. What is the velocity of the resulting combined mass? Round your answer to 2 decimal places.

A 5.0 kg fish moving at 6.6 m/s eats a 1.5 kg fish at rest. Neglecting friction, what is the velocity of the fish after his lunch?

A 65 g bullet is shot at 400 m/s into a 3 kg block of wood at rest. How much kinetic energy is lost in this collision?

A ballerina spins initially at 1.5 rev/s when her arms are extended. She then draws in her arms to her body and her moment of inertia becomes 0.88 kg · m², and her angular speed increases to 4.0 rev/s. What was her initial moment of inertia?

A 0.005 kg coin moving to the right at 0.25 m/s makes an elastic head-on collision with a 0.015 kg coin that is initially at rest. After the collision, the 0.005 kg coin moves to the left at 0.125 m/s. Find the final velocity of the other coin.

20. A puck with a mass m1 = 50 g moving at 1.0 m/s approaches a stationary puck with a mass m2 = 100 g on a frictionless air table, and they undergo a sudden two-dimensional elastic collision. After the collision, both pucks have identical speeds, but travel in different directions. What is the angle between the original and final paths of puck with mass m₁? 60° 150° 90° 30° 120°

A baseball of mass 0.152 kg, travelling horizontally at 37.5 m/s [E], collides with a baseball bat. The collision lasts for 1.15 ms. Immediately after the collision, the baseball travels horizontally at 49.5 m/s[W]. (a) Determine the initial momentum of the baseball. (b) What is the average force applied by the bat to the baseball? (c) Determine the ratio of the magnitude of this force to the magnitude of the force of gravity on the baseball.

Two 1 kg balls move away from each other, one traveling 2 m/s to the right, the other 1 m/s to the left. What is the magnitude of the total momen- tum of the system? Answer in units of kg. m/s. Answer in units of \rm kg\cdot m/s part 2 of 2 Two 1200 kg cars drive east; the first mov- ing at 35 m/s, the second at 30 m/s. What is the magnitude of the total momen- tum of the system? Answer in units of kg. m/s.

A soccer ball with a mass of 0.434 kg approaches a player horizontally with a speed of 16.0 m/s. The player kicks the ball with her foot, which causes the ball to move in the opposite direction with a speed of 22.7 m/s. (a) What magnitude of impulse (in kg m/s) is delivered to the ball by the player? (b) What is the direction of the impulse delivered to the ball by the player? Opposite to the ball's initial velocity Perpendicular to the ball's initial velocity In the same direction as the ball's initial velocity The magnitude is zero. (c) If the player's foot is in contact with the ball for 0.0600 s, what is the magnitude of the average force (in N) exerted on the player's foot by the ball?

In principle, when you fire a rifle, the recoil should push you backward. How big a push will it give? Let's find out by doing a calculation in a very artificial situation. Suppose a man standing on frictionless ice fires a rifle horizontally. The mass of the man together with the rifle is 70 kg, and the mass of the bullet is 10 g. For the steps and strategies involved in solving a similar problem, you may view a Video Tutor Solution. Part A | If the bullet leaves the muzzle at a speed of 500 m/s, what is the final speed of the man? Express your answer with the appropriate units.

A 64 kg canoeist stands in the middle of her canoe. The canoe is 3.1 m long, and the end that is closest to land is 2.6 m from the shore. The canoeist now walks toward the shore until she comes to the end of the canoe. Suppose the canoeist is 3.3 m from shore when she reaches the end of her canoe. What is the canoe's mass?

You are holding a shopping basket at the grocery store with two 0.63-kg cartons of cereal at the left end of the basket. The basket is 0.91 m long. Where should you place a 1.9-kg half gallon of milk, relative to the left end of the basket, so that the center of mass of your groceries is at the center of the basket?

If the speed of the dart is vo just before it strikes the apple, how high does the apple move upward because of its collision with the dart? Express your answer in terms of the acceleration due to gravity g, and some or all of the variables v0 and M.

Consider the following two-car accident: Two cars of equal mass m collide at an intersection. Driver E was traveling eastward, and driver N, northward. After the collision, the two cars remain joined together and slide, with locked wheels, before coming to rest. Police on the scene measure the length d of the skid marks to be 9 meters. The coefficient of friction between the locked wheels and the road is equal to 0.9. Each driver claims that his speed was less than 14 meters per second (about 31 mph). A third driver, who was traveling closely behind driver E prior to the collision, supports driver E's claim by asserting that driver E's speed could not have been greater than 12 meters per second. Take the following steps to decide whether driver N's statement is consistent with the third driver's contention. ▼ Part C Write an expression for the work Wfric done on the cars by friction. Express your answer symbolically in terms of the mass m of a single car, the magnitude of the acceleration due to gravity g, the coefficient of sliding friction, and the distance d through which the two-car system slides before coming to rest. View Available Hint(s) Wfric= Sub Part D Un = AEO Using the information given in the problem introduction and assuming that the third driver is telling the truth, determine whether driver N has reported his speed correctly. Specifically, if driver E had been traveling with a speed of exactly 12 meters per second before the collision, what must driver N's speed have been before the collision? Submit Express your answer numerically, in meters per second, to the nearest integer. Take g, the magnitude of the acceleration due to gravity, to be 9.81 meters per second per second. View Available Hint(s)

Two cars collide at an intersection. Car A, with a mass of 1900 kg, is going from west to east, while car B, of mass 1400 kg, is going from north to south at 12 m/s. As a result of this collision, the two cars become enmeshed and move as one afterwards. In your role as an expert witness, you inspect the scene and determine that, after the collision, the enmeshed cars moved at an angle of 65° south of east from the point of impact. Part A How fast were the enmeshed cars moving just after the collision? Express your answer in meters per second. Part B How fast was car A going just before the collision? Express your answer in meters per second.