Cheryl has just climbed the steps of the metro bus. she begins walking 10 meters to the back of the bus at a constant speed of 3 miles per hour. at the same time, the bus begins moving forward at a constant speed of 3 miles per hour. when cheryl arrives at the back of the she will have moved 10 meters relative to the earth. she will not have moved relative to the earth. she will not have moved relative to the bus. she will have moved 20 meters relative to the earth.