A train passes by an little boy at the depot. as is moves away from the boy at 65 m/s, the whistle emits a feaquency of 4500hz. what freaquency does the little boy hear as the train barrels off into the distance? speed of sound in air is 343 m/s

An astronomer at the equator measures the doppler shift of sunlight at sunset. from this, she calculates that earth’s tangential velocity at the equator is 465 m/s. the centripetal acceleration at the equator is 3.41  10 2 m/s 2 . use this data to calculate earth’s radius.

In a system, when potential energy decreases, then entropy also decreases. true false

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.