Buoyancy

Roads, Rails and Race cars

What Forces act on a Boat?

Gravity

Buoyancy

Buoyancy Definition

• The force on a body that allows it to float or to rise when submerged in a fluid

• The buoyant force exerted on an object by a fluid is equal to the weight of the fluid the object displaced

Fun Tips

• Buoyancy always acts through the center of the volume of the object displacing the fluid 

• The center of mass of the boat should be well below the center of submerged volume of the boat to prevent the boat from tipping– This can be demonstrated with a tall bobber and a

weight. If the weight is mounted on the top of the bobber, the bobber will tip upside down. If it is mounted on the bottom, it will stay upright.

Videos

• http://www.youtube.com/watch?v=gh5xu35bAxA

• https://www.youtube.com/watch?v=FSGeskFzE0s

Activity – Penny Boats• Construct your penny boat using only one piece of

the heavy duty aluminum foil provided• Predict how many pennies your boat will hold:

_______• Slowly add pennies to your boat. Once water

enters the boat, or if any part of the boat touches the bottom of the container, your turn is over

• The last penny added will not count in the total amount held