Tides

Gravity is a force, and it weakens with _____

• distance
• time
• velocity
• acceleration

When calculating gravity, we measure from _____

• the center of mass of an object
• the surface of an object
• sea level
• the closest point to a second object

Right now, how far are you from the center of the Earth?

• about 64 km
• about 640 km
• about 6,400 km
• about 64,000 km

The change in the force of gravity over distance is what astronomers call _____

• the dynamic force
• the concentric force
• the tidal force
• centripetal force

The overall effect of the tidal force is to _____

• compress an object
• stretch an object
• apply a shear force to an object
• rotate an object

Compared to the center, the side of Earth facing the Moon feels a _____ pull toward the Moon

• sideways
• intermittent
• faster
• stronger

Where the tidal force is strongest, we say it's _____

• low tide
• high tide
• neap tide
• no tide

Where the tidal force is weakest, we say it's _____

• low tide
• high tide
• spring tide
• no tide

What is the time between high tide and low tide?

• about 2 hours
• about 6 hours
• about 12 hours
• about 24 hours

There are two high tides and two low tides every _____

• hour
• day
• week
• month