When a balloon is filled with Helium and floats in the air, the Helium provides the Buoyant force. True or False?​

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When an object is heated it contracts. a. true b. false

You are traveling in a car going at a constant speed of 100km/h down a long, straight highway. you pass another car going in the same direction which is traveling at a constant speed of 80km/h. as measured from your car's reference frame this other car is traveling at −20km/h. what is the acceleration of your car as measured from the other car's reference frame? what is the acceleration of the other car as measured from your car's reference frame?