Kinetic Energy etc. Please check.

AI Thread Summary
The discussion revolves around calculating the translational speed, kinetic energy, and angular velocity of a toy car with a flywheel. The toy car, with a mass of 0.180 kg and a flywheel moment of inertia of 4 x 10^-5 kg.m², is claimed to reach a scale speed of 700 km/hr. The actual translational speed of the toy car is determined to be 35 km/hr. The kinetic energy stored in the flywheel, when converted to translational kinetic energy, is calculated to be approximately 8.51 Joules. Finally, the initial angular velocity required to store this energy in the flywheel is found to be 652.3 rad/s.
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Homework Statement


When a toy car is rapidly scooted across the floor, it stores energy in a flywheel. The car has a mass 0.180 kg, and its flywheel has a moment of inertia 4 x 10-5 kg.m². The car is 15.0cm long. An advertisement claims that the car can travel at a scale speed of up to 700 km.hr-1. The scale speed is the speed of the toy car multiplied by the ratio of the length of an actual car to the length of the toy. Assume a length of 3.0 m for a real car.
a) For a scale speed of 700 km.hr-1, what is the actual translational speed of the toy car?
b) If all the kinetic energy that is initially in the flywheel is converted to translational kinetic energy of the toy, how much energy is originally stored in the flywheel?
c) What initial angular velocity of the flywheel was needed to store the amount of energy calculated in part b)?



Homework Equations



Subscript t = toy car; r = real car; f = flywheel; s = scale


The Attempt at a Solution



a)Vs = Vt x lr/lt
Vt = 700/20 = 35km/hr

b)Kf= kt= 1/2 mtVt2
= 1/2 x 0.18 x 9.722
= 8.51J

c) K = 1/2Iw2 = 8.51J
8.51 = 1/2 x 4 x 10-5 x w2
w = 652.3 rad/s
 
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Yep all right
 
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Hey, was this for an assignment or mastering physics online crap??
 

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