Fluids can exert a force on objects
If you push a balloon underwater, why does the water level rise?
The water and the balloon can't be in the same place at the same time, so the balloon displaces the water causing the water level to rise.
What happens if you apply pressure to a gas?
The volume of the gas decreases
In physics, what is work?
Work is defined as the use of force to move an object some distance
I am holding a textbook up so the class can see. Is this work?
Why do hydraulic machines use a liquid instead of a gas to transmot a force?
The volume of the liquid does not change much
What determines whether an object will float in a fluid?
The densities of both the object and the fluid.
What is the equation to calculate density?
Density = Mass / Volume
What is the formula used to calculate work?
W=Fd
If I apply a large force to an object but it does not move, have I done work?
No, as work is only done when a force moves an object.
How does someone playing the piano do work?
By pressing down on the keys
Why is it easier to lift a heavy rock in water?
The buoyant force pushes upwards, reducing the net force needed to lift the rock
If I place a marble with a density of 2 g/cm3 in a glass of apple juice that has a density of 1.05 g/cm3, what will happen to the marble? Why?
As the marble is more dense than the apple juice, the marble will sink. This is because the marble has more weight than the weight of the fluid it displaces.
A sinking object has a weight that is greater than the buoyant force acting on it.
If I lift an object with a weight of 5000N to a height of 3.5 meters, how much work has been done?
17,500 joules
How can a bowling ball do work?
The bowling balls do work on the pins
Why does decreasing the volume of an object decrease the buoyant force acting on it when it is in a fluid?
Decreasing the volume of an object decreases the volume of the liquid it displaces, which decreases the buoyant force
If a wooden ball has a mass of 200g and a volume of 25cm3 what is its density?
8 g/cm3
If I place an object in a fluid that has a weight that is greater than the fluid it displaces, what happens to the object?
It sinks
If I change the direction of the applied force, what happens to the amount of force that is doing work?
It changes the amount of the applied force doing work
How are work and force related?
Work is the amount force applied to an object over a certain distance.
How does the device on the back of a racecar take advantage of Bernoulli's priniciple?
Race cars have a device on them called a wing. It causes more pressure to be applied on the top of the car, pushing it onto the road and increasing friction between the tires and the road
State Bernoulli's principle
The faster a fluid moves, the less pressure it exerts on surfaces or openings over which it flows
How do airplane wings work to create lift using Bernoulli’s principle?
Wings increase the speed of the air over the top of the wing, reducing pressure. They decrease the speed of the air under the wing, increasing the pressure.
If I decrease the distance in which an object has been moved, what must happen to keep work the same?
The force must increase
If I did 2000j of work by moving an object a distance of 10 meters, how much does the object weigh?
200 N
State Pascal's principle
When an outside pressure is applied at any point to a fluid in a container, that pressure is transmitted throughout the fluid with equal strength