a) how fast must a 2.0 kg mass move to have a kinetic energyof 9.0 j? does the k

Question

a) how fast must a 2.0 kg mass move to have a kinetic energyof 9.0 j? does the kinetic energy of the mass change if the massreverses direction without changing its speed? b) by what factor must you increase the velocity of a mass todouble its kinetic energy? a) how fast must a 2.0 kg mass move to have a kinetic energyof 9.0 j? does the kinetic energy of the mass change if the massreverses direction without changing its speed? b) by what factor must you increase the velocity of a mass todouble its kinetic energy?

Explanation / Answer

Kinetic energy is the energy possessed by a body byvirtue of its motion. Also, KE =0.5*m*v.v So, v = [2*KE/m] = [2*9.0/2.0] = 3.0m/s Since kinetic energy is a function ofv.v, it is independent of the sign/direction ofv So, reversing direction doesn't change the speed. In order to double the KE, 0.5*m*v'*v' = 2*0.5*m*v*v => v'2 = 2v2 => v' = (2)v So, reversing direction doesn't change the speed. In order to double the KE, 0.5*m*v'*v' = 2*0.5*m*v*v => v'2 = 2v2 => v' = (2)v

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