Show:
chemistry
moments
density
pressure
mixed (life application)
100

Group 1 trend down the group (reactivity)

Reactivity increases down the group

100

What is a moment? formula?

The turning effect of a force around a pivot. Moment = Force × Distance.

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

Table salt formula

NaCl

200

When can we tell that moments are balanced?

When clockwise and anticlockwise moments are equal

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

Hand warmers are example of which reaction

exothermic

300

What is exothermic and endothermic reactions

Exothermic reaction: releases heat → gets hot (combustion, respiration).

Endothermic reaction: absorbs heat → gets cold (photosynthesis, melting ice).

300

Longer spanner or short spanner has more moments

longer

300

Heavier object with same volume has ____ density

higher

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

Door handles are far from hinges to increase

Moment

400

Hydrochloric acid + Sodium hydroxide

Sulfuric acid + Magnesium

Sodium chloride + Water

Magnesium sulfate + Hydrogen

400

What happens to the turning effect if the force is applied close from the pivot?

moment decreases

400

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.

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

Speeds up reactions in living things

enzymes

500

Neutralization → 

Metal + acid →

Metal carbonate + acid→

salt + water

salt + hydrogen

salt + water + CO₂

500

A force of 10 N is applied 0.5 m from the pivot. Calculate the moment about the pivot.

5 N·m

500

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.

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

Tractor tires reduce ground pressure by increasing

Area