When several objects move with the same constant speed

PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Work Energy and Power · Work Energy and Power

Problem

When several objects move with the same constant speed, their kinetic energies are found to vary linearly with mass. For two of the objects the following data are obtained: Mass m1=2 kgm_1 = 2\,\text{kg}, Kinetic energy K1=18 JK_1 = 18\,\text{J} Mass m2=5 kgm_2 = 5\,\text{kg}, Kinetic energy K2=45 JK_2 = 45\,\text{J} Using this information, answer the questions below. (i) Determine the speed common to all the objects. (ii) Calculate the kinetic energy of an object of mass 4 kg4\,\text{kg} moving at this speed. (iii) If another object moving at the same speed possesses 81 J81\,\text{J} of kinetic energy, find its mass.

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