To apply the principle of work and energy to a system of particles. The principle of work and energy can be extended from one particle to include a system of particles as follows: ∑T1+∑U1−2=∑T2 where ∑T1 is the system's initial kinetic energy, ∑U1−2 is the sum of the work done by all external and internal forces acting on the system's particles, and ∑T2 is the system's final kinetic energy. When the particles either are undergoing only translational motion or are connected by inextensible cables, the internal forces of the particles negate each other; only the external forces are required in the principle of work and energy. When frictional forces are present, the work done by the frictional force is UF=μkNs, where μk is the coefficient of kinetic friction, N is the normal force, and sis the body's displacement. In this equation, the work done by friction represents both theexternal work of friction and the internal work that is converted into various forms of internal energy, such as heat. As shown, a 300 lb bungee jumper wants to jump from the top of a 215 ft high bridge and be able to just touch the water below(Figure 1). Given that the bungee cord has a spring constant of 6.81 lb/ft , what should the bungee cord's relaxed length, l, be for this jump?
To apply the principle of work and energy to a system of particles.
The principle of work and energy can be extended from one particle to include a system of particles as follows:
∑T1+∑U1−2=∑T2
where ∑T1 is the system's initial kinetic energy, ∑U1−2 is the sum of the work done by all external and internal forces acting on the system's particles, and ∑T2 is the system's final kinetic energy. When the particles either are undergoing only translational motion or are connected by inextensible cables, the internal forces of the particles negate each other; only the external forces are required in the principle of work and energy.
When frictional forces are present, the work done by the frictional force is UF=μkNs, where μk is the coefficient of kinetic friction, N is the normal force, and sis the body's displacement. In this equation, the work done by friction represents both theexternal work of friction and the internal work that is converted into various forms of internal energy, such as heat.
As shown, a 300 lb bungee jumper wants to jump from the top of a 215 ft high bridge and be able to just touch the water below(Figure 1). Given that the bungee cord has a spring constant of 6.81 lb/ft , what should the bungee cord's relaxed length, l, be for this jump?
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