Jack and Jill are standing on a crate at rest on the frictionless, horizontal su
ID: 2093095 • Letter: J
Question
Jack and Jill are standing on a crate at rest on the frictionless, horizontal surface of a frozen pond. Jack has a mass of 74.0kg , Jill has a mass of 46.0kg , and the crate has a mass of 15.5kg . They remember that they must fetch a pail of water, so each jumps horizontally from the top of the crate. Just after each jumps, that person is moving away from the crate with a speed of 4.50m/s relative to the crate. Part A What is the final speed of the crate if both Jack and Jill jump simultaneously and in the same direction? (Hint: Use an inertial coordinate system attached to the ground.) Part B What is the final speed of the crate if Jack jumps first and then a few seconds later Jill jumps in the same direction? Part C What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction? PLEASE HELP. WILL RATE 5 STARS. THANKS! Jack and Jill are standing on a crate at rest on the frictionless, horizontal surface of a frozen pond. Jack has a mass of 74.0kg , Jill has a mass of 46.0kg , and the crate has a mass of 15.5kg . They remember that they must fetch a pail of water, so each jumps horizontally from the top of the crate. Just after each jumps, that person is moving away from the crate with a speed of 4.50m/s relative to the crate. Part A What is the final speed of the crate if both Jack and Jill jump simultaneously and in the same direction? (Hint: Use an inertial coordinate system attached to the ground.) Part B What is the final speed of the crate if Jack jumps first and then a few seconds later Jill jumps in the same direction? Part C What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction? PLEASE HELP. WILL RATE 5 STARS. THANKS! Part A What is the final speed of the crate if both Jack and Jill jump simultaneously and in the same direction? (Hint: Use an inertial coordinate system attached to the ground.) Part B What is the final speed of the crate if Jack jumps first and then a few seconds later Jill jumps in the same direction? Part C What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction? PLEASE HELP. WILL RATE 5 STARS. THANKS! Part B What is the final speed of the crate if Jack jumps first and then a few seconds later Jill jumps in the same direction? Part C What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction? PLEASE HELP. WILL RATE 5 STARS. THANKS! Part C What is the final speed of the crate if Jill jumps first and then Jack, again in the same direction? PLEASE HELP. WILL RATE 5 STARS. THANKS!Explanation / Answer
A) AS THEY JUMP TOGETHER
BY MOMENTUM CONSERVATION
(74+46)(4.5-V1)=15.5V1
=>V1=3.99 M/S
B)JACK JUMPS FIRST
BY MOMENTUM CONSERVATION
(74)(4.5-V1)=(15.5+46)V1
=>2.45 M/S
NOW JILL JUMPS
BY MOMENTUM CONSERVATION
61.5*2.45=15.5V1-46*(4.5-V1)
=>V1=5.81 M/S
C)
JILL JUMPS FIRST
BY MOMENTUM CONSERVATION
(46)(4.5-V1)=(15.5+74)V1
=>1.53 M/S
NOW JACK JUMPS
BY MOMENTUM CONSERVATION
89.5*1.53=15.5V1-74*(4.5-V1)
=>V1=5.25 M/S
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