A police car is moving east at 20m/s towards a driver who is moving west at 25m/s. The police car emits a frequency of 900Hz. What frequency is detected by the driver? The speed of sound at the time of this occurrence was 343m/s.

Bone-strengthening physical activity done increases bone-mineral content and bone density in youth.

Imagine you are riding on a yacht in the ocean and traveling at 20 mph. you then hit a golf ball at 100 mph from the deck of the yacht. you see the ball move away from you at 100mph, while a person standing on a near by beach would observe your golf ball traveling at 120 mph (20 mph + 100 mph). now imagine you are aboard the hermes spacecraft traveling at 0.1c (1/10 the speed of light) past mars and shine a laser from the front of the ship. you would see the light traveling at c (the speed of light) away from your ship. according to einstein’s special relativity, how fast will a person on mars observe the light to be traveling? a) 0.1c (1/10 the speed of light) b) c (the speed of light) c)1.1c (c+0.1c)

How many atoms of nitrogen are in the chemical formula ni(w on