Show:
Buoyancy and Archimedes Principle
Pascal’s Principle
Pressure and Bernoulli’s Principle
Density
Misc.
100
When do objects float? (explain using buoyant force)
When the buoyant force is greater than the weight.
100
How do hydraulic lifts help us lift up heavy objects?
When we put in a little bit of force, it can multiply the force on the other end
100
Would a person put more pressure on a bed by lying on it or standing on it? Why?
Standing, because the surface area of the person’s feet would be less than the surface area of their entire body
100
What is an object’s density?
It is it’s mass (how much it weighs) divided by its volume (how much space it takes up)
100
What allows Parachutes to slow people down when skydiving?
Drag forces push up against the person’s falling motion and slows it down.
200
If an object has a volume of 40cm^3, what is the buoyant force of water acting on the object?
40Newtons
200
What is Pascal’s Principle? (Be very specific)
When pressure is added to a fluid in a closed container, the same pressure is applied everywhere in the fluid.
200
A box that weighs 900g takes up 30cm^2 of space on a table. How much pressure is the box putting on the table?
30 Pascals
200
A ball has a mass of 5g and a volume of 10cm^3, what is it’s density? Will it sink or float in water?
Density=0.5 g/cm^3, float
200
A liquid and a gas are both fluids. What’s the difference between the two?
A liquid always occupies the same volume but a gas does not.
300
Which has a greater buoyant force? A ball that weighs 10g and has a volume of 30cm^3, or a ball that weighs 30 grams and has a volume of 10cm^3
The ball that has a volume of 30cm^3 because it displaces more water.
300
Why does Pascal’s principle only apply to fluids that are in a closed container?
Fluid can escape from an open container when pressure is added, so the pressure would not be the same everywhere.
300
An object that has a surface area of 30cm^2 is adding 600 Pa of pressure onto a chair. How much does the object weigh?
18,000 grams because its weight is equal to how much force it is exerting on the chair.
300
When you combine water with oil, why does the oil form a layer on top of the water rather than mixing together?
The oil is less dense than water so it floats on top.
300
What is the density of water? Explain mathematically why that is the case.
Density of water is 1g/cm^3 because 1 gram of water is equal to 1cm^3 of water so mass/volume will always be 1.
400
A scuba diver has 200 N of buoyant force pushing him up when he is at 20m below sea level. What would be the buoyant force when he is at 40m below sea level?
200N because buoyant force never changes
400
Why does an eyedropper sink when you squeeze a closed water bottle?
The pressure is increased everywhere, so water is pushed up into the eyedropper, causing it to become denser.
400
What happens when you blow between two strips of paper? Why?
They come together because when the air is travelling fast, the pressure is lower, so the higher pressure on the outside of the papers will push them together.
400
Why does pasta sink in water but float in honey?
Pasta is more dense than water but less dense than honey
400
Why is it harder to walk in water than on land?
Water is more dense so it creates a greater drag force that slows you down.
500
An object has a volume of 10cm^3 and it sinks in water. What does that say about the object’s weight?
The object weighs more than 10 grams
500
If we put 20N of force onto one end of a hydraulic lift that has a surface area of 2m^2, how much force would be on the other end which has a surface area of 6m^2?
60 Newtons
500
According to Bernoulli’s Principle, why do shower curtains sometimes get sucked in towards the bathtub when someone is taking a shower?
When the water is running quickly, the pressure is lower on the inside of the bathtub so the curtain gets pushed in.
500
One Aluminum block has a volume of 4cm^3, and another Aluminum block has a volume of 8cm^3. Which has a greater density?
They have the same density because they are made of the same material.
500
Is air pressure more or less dense in colder places? Why?
Air pressure is higher because air molecules don’t move as far away from each other and makes it more dense.