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A $15.0-\mathrm{kg}$ fish swimming at 1.10 $\mathrm{m} / \mathrm{s}$ suddenly gobbles up a $4.50-\mathrm{kg}$ fish that is initially stationary. Neglect any drag effects of the water. (a) Find the speed of the large fish just after it eats the small one. (b) How much mechanical energy was dissipated during

this meal?

(a) $v_{2}=0.846 \mathrm{m} / \mathrm{s}$

(b) $-2.10 \mathrm{J}$

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Cornell University

Hope College

University of Winnipeg

McMaster University

{'transcript': "Well, we have to. Fish is a and B the big ones masses 15.0, uh, kilogram. So I m OK, that's the mass off big big one. And it's equal dude, 15.0 kilogram, right? And the small ones mass is 4.5 kilograms. So small wounds Man sees 4.5 cereal kilogram Well taken. The initial direction is the positive direction we have the big piece of lost e before the collegian. Well before the cook Origen the lost ease the A one and that is equal to 1.10 Me too per second and the small our fish were lost before the collision is we B one and that is equal to zero meters per second. Well, we know that in collision off all kinds, since there is no external net force on the system are the total momentum before the collision. Nichols. The total momentum are off the religion. Therefore be one is equal to be to right momentum before collision is equal to momentum after collision. Well, if the collision is between two particles and be, then we could B one right? Let's speed be one is equal to be into less speedy, too. Must be be to where the momentum off particle is given by so momentum off particle is given by most times velocity. But let's call this equation of a one. Now we can write the courtroom religion, the question in the following form. Let's write down here Marcel's In times we a one bless Marcelo b times we b one, and that is equal to Marcelo Dinz. We ate too less muscle being times we be to. And let's say this is equity number to this equation is equity number two Right now? Let's to party. So we depart in well, neglecting what Straight in fact means that there is no external net force. So the momentum is concerned also after the collision the big fish it's the small one. So they have the same final velocity. So we have be a to is equal to we be too is equal to we to now we plug our values for M A M be re Evan and we be gone and substitute for we two in three. Question number two. So we have 15.0 15 points. It'll into one point once you don't this 4.5 Sydell in 20 that is equal to 15 multiply by. We do this 4.5 cedar times we do and solving for we to We two is equal to 15.0 times 1.10 divided by 15.0, this 4.5 CDO and that is equal to zero point 846 Me, too, per second. And now we do part being well, let's calculate the Connecticut before the religion. So care one is equal to okay, a one escapee, one its kinetic energies okay, and be how then is equal to one divided by two into 15.0 into 1.10 Hold square. Ah, bless Zito, and that is equal to 9.75 Julie and the kinetic energy after the collision is given by so kinetic energy after the collision is scared to and get two is equal to key to less baby to on that is equal to one divided by toe into ah, 15.0 this 4.5 into zero point it 46 old square, and that is equal to six point 981 Jewell and no change in kinetic energy. Physical took a to minus K one that is equal to six point buying it one minus 9.75 that is equal to minus 2.94 Jules. Since the fishes are in the water, there is always a force exerted by water opposite to gravity, so we can neglect the gravitational potential. Energy for the kinetic energy is all the mechanical interceding for the disparaged mechanical energy. Giving this Tom meal is 2.94 Jewell. So it is, he added, mechanical energy is equal to 2.9 or jewels."}