Calculating density
Calculating pressure
density
pressure
real Life application
100
What do you need to know in order to find an objects density? Explain what those things are.
Mass, how much stuff (matter) something has and Volume, how much space something takes
100
What do you need to know in order to calculate pressure? (Explain what those two things mean.)
Force, the amount something pushes or pulls. Area, the amount of floor space something takes. (touching area)
100
What is density?
It is a measure of how crowded the particles of a substance are. It is calculated by dividing the mass by the volume.
100
What is pressure?
It is the amount of force put onto a certain area.
100
The walls at the bottom of a pool need to be thicker than the walls at the top of the pool. Explain why.
The walls at the bottom experience more pressure from the water because of the weight of all the water from above, so the walls need to be thicker and stronger at the bottom.
200
What is the density of an object that is 3cm3 and 6 grams?
2 grams per cm3
200
What is the pressure of a shoe with an sole area of 100cm3 and a force of 500N?
500N/100cm3 = 5N/cm3 (So for every Square centimeter, there is about 0.5kg of force pushing on it.)
200
Why do gases generally have a lower density than solids?
Gas particles have a lot of energy making the particles fly away from each other, so the particles are spread out and not dense.
200
Why does a pushpin have a flat side and a pointy side?
Pressure = force/area The large area of the flat side with a little force to push it creates a small amount of pressure. Let's say the area is 1cm2 and the force is 5N. The pressure applied is 5N/cm3. The pointy side means a very small area gets all the force, applying a lot of pressure. Let's say the pointy side is 0.01cm2. The pressure is now 500N/cm2.
200

The weight of a 100 N laser printer is spread over 0.5m2. What is the pressure it exerts?

200 Pa

300
An object has a density of 3kg per m3. It has a volume of 6m3. What is its mass?
18kg
300
What is the area of a block that has a pressure of 6N/m2 and a force of 60N?
10m2
300
1cm2 is equal to?
1 mL
300
If a person wears high heels on the moon and on Earth, does the same pressure get applied to the different surfaces? Why?
No. Since there is less gravity on the moon, the force of the person pushing down on the moon's surface is less. If the person is 600N on Earth, they would be 100N on the moon. The area of their feet would stay the same, but the pressure would be different.
300

If I take a plastic bottle filled with water, no lid and poke two holes in it, one at the top and one at the bottom, which of the holes will squirt out water with more force and why?

The hole at the bottom since the weight of the water creates more pressure at the bottom than at the top.

400
An object has a density of 5grams per cm3. If the mass is 10 grams, what is the volume?
2 cm3
400
What is 1 Pascal equal to?
1 N per square meter
400
Look at these three object and say which will float or sink in water and why. A 0.3g/cm3 B 1.1 g/cm3 C 1.0g/cm3
The density of water is 1g/cm3. So A will float since its density is lower than water. B will sink. C is neutrally buoyant, meaning it neither sinks or floats.
400
Does the way a person stand have an effect on the pressure they exert on the Earth? Give examples.
Yes. A person who lies down flat will have more area on the surface and than standing on two feet. If they stand on their toes, even more pressure is exerted, and if they stand on the toes of only one foot, even more because the area gets smaller and smaller, even though the force remains the same.
400

You see a box floating in the middle of the classroom. What hypotheses could you make about the box or the air in the room?

The air is denser than the box so either the box is made of something less dense than air, of the air is made of something very dense.

500
Which has the higher density? Object A has a mass of 100 grams and a volume of 20cm3. Object B has a mass of 200 grams and a volume of 50cm3.
Density of A is 5grams/cm3. Density of B is 4grams/cm3. A has higher density.
500
Which applies more pressure? A: A 60N box with an area of 10m2 B: A 100N box with an area of 20m2
A has a pressure of 6Pascal and B has a pressure of 5pascal, so A applies more pressure.
500
A ship is made of metal but still floats on the ocean. Why?
The ship also holds a large volume of air which changes the total density of the ship, making it less dense than water. We say the ship is able to displace (push away) a mass of water equal to the mass of the ship.
500
What is the difference between weight and mass?
Mass is the amount of matter something has, but weight is the effect of gravity on the mass. So mass stays the same on different planets, but weight changes as gravity changes.
500

A skier weighs 600 N and exerts a pressure of 2,500 Pa on the snow. What is the area of the skis?

4.1 m2

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