What source of earths magnetic field is

A900 kg roller coaster car is travelling westward on the track and begins to slow down from 18m/s to 2m/s. how long does it take the roller coaster car to decelerate if the force acting on the car to slow it is 7024n? how far does the roller coaster travel during this time?

In the image, the arrow is pointing to a celestial object. which attribute disqualifies the object from being a planet?

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)