Overcoming Frozen Pond Friction with a Thrown Textbook

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A 680 N student on a frictionless frozen pond attempts to reach the shore by throwing a 2.6 kg textbook at 10.0 m/s. Using conservation of momentum, the student's mass is calculated to be 69.4 kg. The momentum equation shows that the student's velocity after throwing the book is -0.37 m/s. By applying kinematic equations, it is determined that the student takes 16 seconds to reach the south shore. The discussion emphasizes the importance of momentum conservation in solving the problem.
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Homework Statement



A 680 N student stands in the middle of a frozen pond having a radius of 6.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 2.6 kg physics textbook horizontally toward the north shore at a speed of 10.0 m/s. How long does it take him to reach the south shore?

Homework Equations



p=m*v

F=p/t


The Attempt at a Solution



?
 
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Vision5 said:

Homework Statement



A 680 N student stands in the middle of a frozen pond having a radius of 6.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 2.6 kg physics textbook horizontally toward the north shore at a speed of 10.0 m/s. How long does it take him to reach the south shore?

Homework Equations



p=m*v

F=p/t


The Attempt at a Solution



?

Please at least attempt a solution next time. I'll help you out anyway because I'm bored.

The basic strategy behind solving this problem centers on conservation of momentum. Before we get to that, however, we need to find out the mass of the student. We know the student's weight, W, and from that we can figure out the mass:

W = m_sg

>> 680 N = m_sg

>> m_s = 69.4 kg

With that out of the way, we can use conservation of momentum:

P_i = P_f

>> m_bv_b + m_sv_s = m_bv_b + m_sv_s

The left side of the equation is 0. There is no initial momentum. The book and the person are both at rest. This leaves us with the following equation:

0 = m_bv_b + m_sv_s

Plug everything in and solve for the velocity of the student:

v_s = -.37 m/s

Now it's simple kinematics:

distance = velocity * time

Solve for time:

t = 16 seconds
 


I apologize I had attemped it myself i just didn't want to write something completely wrong on here i thought it would just complicate things. Will do next time though.

Thank you for the help I appreciate it. Very easy to follow.

-vision
 
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