Forces: online assignment for 9CB

Dear learners
   watch the following videos and submit your online test that has been emailed you on your gmail accounts

https://www.youtube.com/watch?v=LYXGlXMi6_c

https://www.youtube.com/watch?v=kKKM8Y-u7ds

Regards

Kashif Jamal

 Heat Capacity:

Heat Capacity, C, of a body is defined as the amount of heat (Q) required to raise its temperature (θ) by one degree, without going through a change of state. 

• Amount of heat needed to raise the temperature of an object depends on the mass of the object.
• Heat capacity also depends on the material of the object. Some materials are harder to heat up than others. In order to record 1°C increase in temperature, liquids would require more heat energy than solids.
• SI. unit of heat capacity is joule per kelvin (J K^-1) or joule per degree Celsius (J °C^-1).

C=QΔθ
 , where
C = heat capacity (JK^-1, J°C^-1)
Q = heat or thermal energy absorbed or released (J)
Δθ = change in temperature (K or °C)

 Specific Heat Capacity: 

Specific heat capacity, c, of a body is defined as the amount of heat (Q) required to raise the temperature (θ) of a unit mass of it by one degree, without going through a change in state.

• When the mass of an object is greater, the object will contain more atoms or molecules than a less massive object made up of the same material. Hence, when the temperature of the objects are raised, the more massive object will require a larger thermal energy than the less massive object. (Analogy: The more massive object has more “mouths” to feed) It is thus more common to consider the heat capacity per unit mass or specific heat capacity of the body.

SI unit of specific heat capacity is joule per kilogram per kelvin (J kg^-1 K^-1) or joule per kilogram per degree Celsius (J kg^-1 °C^-1)
Q=mcΔθ

 

 

Thermal Energy and Temperature

Thermal Energy:
 Thermal energy is a form of internal energy. Thermal energy is possessed by all material matter and manifest as the random motion of atoms and small particles. The amount of thermal energy depends on the temperature of the matter.

Temperature:
Temperature is a measure of the degree of hotness or coldness of a body.

Transfer of Thermal Energy:
Thermal energy may be transferred from one region to another as a result of a difference in temperature via thermal:

1. conduction 
2. convection 
3. radiation 

Thermal energy flows from a higher temperature object to a lower temperature object. However, this heat exchange will cease when both objects reach thermal equilibrium (same temperature).
Important:
Temperature is not the equivalent of the total energy contained in a body. The total energy contained in a body is comprised of other forms of energy as well.

...determining Density

DENSITY

The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:

where ρ is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight.

• SI unit of density is kilograms per metre cube (kg m^-3). It is a scalar quantity.
• Another common unit of density is g cm−3. 1000 kg m−3=1 g cm−3

ρ=The density of a substance does not change as you move from place to place as the mass and volume does not depend on the gravitational acceleration of the point that the object is at.

Qtn: Why does the cork float and the rock sink in water?
Ans: The density of a substance determines whether it will float or sink in different liquids (or gases).
The cork is less dense than water → it floats in water.
The rock is denser than water → it sinks in water.

About Mass and Weight ......

It's very easy to do when you're not entirely sure of how science actually defines them. Even though they're both linked, I've put together a fairly comprehensive description which, more importantly, is written in layman's terms and not scientific babble!

WHAT IS MASS?

Mass is a scientific measure of the amount of matter an object is made up of. No matter where you are at given moment in time, mass is constant. So, whether you're walking to the shop to stock up on groceries or bouncing around on the moon, your mass is the same.

Some other key points about mass

1. Mass is indestructible. As you've seen above, no matter where you are in the universe your mass will never change
2. Mass can never be zero. What we mean by this is that everything in the universe has mass. If it didn't it simply wouldn't exist
3. Mass is not related to gravity, centrifugal force, etc and these forces have no effect whatsoever on your mass
4. Mass is commonly measured in kilograms and grams.

WHAT IS WEIGHT?

Weight is a form of measurement that is dependent on gravity and, unlike mass, your weight can vary depending on where you are in the universe.

Some key points about weight

1. The weight of an object changes based on where it is. If you've decided to visit the moon to test out this theory then you'll find that, in a matter of hours, you will have slashed your weight by two thirds (in your face, Slimming World!)
2. Weight is a vector and its direction of pull is towards the centre of the planet you're stood on. What? Sorry, I did promise layman's terms: gravity, which is created by the mass of an object, moves towards the centre of the object and it is gravity that determines your, or any other object's, weight.
3. The weight of any given object can go up or down depending on the amount of gravity acting on it. More gravity - the heavier the object. Less gravity - the lighter the object.
4. Unlike mass, weight can be zero. An example of this is an astronaut floating in space - there's no gravity acting on his body and, therefore, he has no weight.
5. Weight is commonly measured in Newtons.

chellenge to reinforce EM waves

You can copy and then paste the content of this general test in a word file and then go through the resources or use your knowledge to fill the blanks properly.

Physics - 5054
Electromagnetic Waves and Properties
10-Cambridge (GCSE)

Can you fill in the blanks with correct words after search!!

1. ____________________ waves are used to penetrate solids and are used in doctor’s offices and as airports.
2. ____________________ is the distance between one point of a wave to the same point in the next wave.
3. ____________________ is the number of waves per unit of time.
4. ____________________ waves occur when the motion of the medium is parallel to the direction of the wave.
5. ____________________ waves have a color spectrum known as ROYGBIV.
6. ____________________ waves disturb matter.
7. The ________________ is the top of a wave.
8. The ________________ is the bottom of a wave.
9. ____________________ is the maximum distance that matter is displaced from the resting position.
10. ___________________ waves are produced by stars and galaxies.
11. ___________________ waves occur when the motion of the medium is at right angles (perpendicular) to the direction of the wave.
12. ___________________ waves are often used in heat lamps.
13. ___________________ waves are utilized by insects to locate nectar.
14. ___________________ waves are transverse waves that disturb electromagnetic fields.
15. ___________________ waves have the shortest wavelength and the highest frequency.
 Thank You...

Sound Waves

In physics, sound is a vibration that propagates as a typically audible mechanical wave of pressure and displacement, through a medium such as air or water. Sound is a mechanical wave phenomenon and is normally associated with our sense of hearing. Sound is a property of vibrating objects.

• Sound is produced by vibrating sources in a material medium. Medium can be any gas, liquid or solid.
• The vibrating sources set the particles of a medium in vibration in such a way that sound travels outwards in the form of longitudinal waves.
• Some of the energy of the vibrations are transmitted over a distance.

I suggest that you should visit miniphysics.com for further details on factors effecting the sound and properties of sound.