Answer:

Explanation:
Speed is equal to distance over time.

The distance is 400 meters and the time is 50 seconds.

Substitute the values into the formula.

Divide.

The speed of the car is 8 meters per second.
Answer:
Magdeburg hemispheres are two half-spheres of equal size. Placing them together traps air between them. This air is merely trapped, and not compressed, so the pressure inside is the same as the pressure of the atmosphere outside the spheres. The spheres thus pull apart with nearly no resistance.
Always getting sleepy after lunch is part of data collection.