A woman is riding a bicycle at 18.0 m/s along a straight road ...

[leilurhhh]

A woman is riding a bicycle at 18.0 m/s along a straight road that runs parallel to and right next to some railroad tracks. She hears the whistle of a train that is behind.
 
  The frequency emitted by the train is 840 Hz, but the frequency the woman hears is 778 Hz. Take the speed of sound to be 340 m/s. (a) What is the speed of the train, and is the train traveling away from or toward the bicycle? (b) What frequency is heard by a stationary observer located between the train and the bicycle?

Question 2

A 2.10-kg hammer is transported to the Moon. The radius of the Moon is 1.74  106 m, its mass is 7.35  1022 kg, and G = 6.67  10-11 N  m2/kg2. What is the gravitational force exerted on the hammer on Earth and on the Moon?
 
  What will be an ideal response?

[johnharpe]

Answer to Question 1

(a) 7.67 m/s, away from the bicycle (b) 821 Hz

Answer to Question 2

20.6 N (on Earth), 3.40 N (on the Moon)

[leilurhhh]

Excellent

[matt95]

TYSM