Physics Unit 6 - Buoyancy & Fluids

How is it possible to lay on a bed of nails?

Because the area of all the nails is large compared to a single nail, pressure will be low

What is the numerical value of the atmospheric pressure on someone?

101,300 Pa

Why don’t one notice the pressure?

You have an internal pressure that counteracts this pressure

Explain why the shower curtain often gets pulled into the shower stall once the water is turned on.

Fast moving fluid (the ongoing water) creates an area of low pressure in the shower. The high pressure wants to move towards the low pressure area pushing inward

Explain why a roof of a house can sometimes be blown off during a hurricane.

High moving air causes pressure to be low on the outside of the roof. Higher pressure inside wants to push upward toward the area of lower pressure

Explain why the ping pong ball stayed in the path of the hair dryer.

Fast moving air on either side of the ball causes the inward force on both sides, cancelling one another out

What physical property determines if an object will float?

Density

Why do steel boats float?

The combined density of steel and air (in the hollows of the boat) is less than density of water

The amount of water displaced is the same as the ______ of the object.

volume

The buoyant force is equal to the _____ of the fluid displaced

weight

If an object is floating

F_B = F_g

If an object is sinking

F_{B ^<}  F_g

If an object shoots out of the water

F_{B ^>} F_g