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Q17PE
Expert-verifiedTwo teams of nine members each engage in a tug of war. Each of the first team’s members has an average mass of 68 kg and exerts an average force of 1350 N horizontally. Each of the second team’s members has an average mass of 73 kg and exerts an average force of 1365 N horizontally.
(a) What is magnitude of the acceleration of the two teams?
(b) What is the tension in the section of rope between the teams?
(a) The magnitude of the acceleration of the two teams is 0.106 m/s2.
(b) The tension in the rope is \(12214.8\;{\rm{N}}\).
Apply Newton’s second law of motion.
\({F_{{\rm{net}}}} = ma\)
\(\left( {{F_2} - {F_1}} \right) = \left( {{m_1} + {{\rm{m}}_2}} \right)a\) …….…………. (i)
Here, Fnet is the net force, n is the number of members, m1 is the average mass of the first team member, m2 is the average mass of the second team member, F1 is the force exerted by the first team members, F2 is the force exerted by the second team members, and a is the acceleration of the two teams.
Substitute 68 kg for m1, 73 kg for m2, 1350 N for F1, and 1365 N for F2 in equation (i), and we get,
\(\begin{array}{c}1365\;{\rm{N}} - 1350\;{\rm{N}} = \left( {68 + 73} \right)\;{\rm{kg}} \times a\\15\;{\rm{N}} = 141\;{\rm{kg}} \times a\\a = \frac{{15\;{\rm{kg}} \cdot {\rm{m/}}{{\rm{s}}^{\rm{2}}}}}{{141\;{\rm{kg}}}}\\a = 0.106\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}\end{array}\)
Hence, the magnitude of the acceleration of the two teams is 0.106 m/s2.
Apply Newton’s second law of motion,
\(T - n{F_1} = n{m_1}a\)
Here, T is the tension in the rope.
Substitute 68 kg for m1, 9 for n, and 1350 N for F1 in the above expression, and we get,
\(\begin{array}{c}T - 9 \times 1350\;{\rm{N}} = 9 \times 68\;{\rm{kg}} \times 0.106\;{\rm{m/}}{{\rm{s}}^{\rm{2}}}\\T - 12150\;{\rm{N}} = 64.872\;{\rm{kg}} \cdot {\rm{m/}}{{\rm{s}}^{\rm{2}}}\\T = \left( {64.872 + 12150} \right)\;{\rm{N}}\\T = 12214.8\;{\rm{N}}\end{array}\)
Hence, the tension in the rope is\(12214.8\;{\rm{N}}\).
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