Ball on a Moving Train

In the picture

1. 1The ball: the object whose motion is watched
2. 2The short arrow: small distance covered in the passenger’s view
3. 3The seated passenger: observer moving with the train
4. 4The long arrow: large distance covered in the platform observer’s view
5. 5The platform person: observer standing still relative to the station

Examples

• A passenger walking down a train aisle: a seatmate sees slow steps, while someone on the platform sees a fast blur.
• A person sitting in a moving car: the driver’s coffee cup seems still, while a roadside pole races backward.

Quiz: Ball on a Moving Train (Age 15)

1. 1

   What does the card say a motion is described relative to?

   • The time measured
   • A chosen reference
   • The object’s speed alone
2. 2

   According to the card, how can the same motion appear from different references?

   • As rest, slow, or fast
   • Always as exactly the same speed
   • Only as an increase in speed
3. 3

   In the card, what does the seated passenger represent?

   • An observer moving with the train
   • An observer standing still relative to the station
   • The object whose motion is watched

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.