FORCES
Energy
Thermal Effects
Liquids and Vapor
100
What is a force?
A force is a push or a pull on an object.
100
Describe the Law of the conservation of Energy.
Energy cannot be made or destroyed, but it can change from one form to another.
100
What is the kinetic particle theory about?
It explains that matter is made up of tiny particles which are constantly in motion. The particles attract each other strongly when close, but the attractions weaken if they move further apart.
100
How does evaporation happen? When does it happen?
Evaporation happens at the surface of the liquid only at all temperatures! Some of the particles at the surface of a liquid have enough kinetic energy to escape. When they escape from the liquid, they are in gas form now.
200
Name 3 types of Forces that exist.
Friction Force...... Tension Force........ Air Resistance Force....... Gravitational Force........ Upthrust....... Drag......... Spring Force......... Magnetic Force.......
200
Give 3 examples of Energy.
Kinetic Energy...Potential Energy...Gravitational Potential Energy...Strain Energy (When you stretch a rubber band)...Chemical Energy...Nuclear Energy...Thermal Energy...Radiated Energy
200
What is internal energy?
Internal energy is the average total kinetic and potential energies of all atoms or molecules in a material. The hotter a material is, the faster its particles move, and the more internal energy it has.
200
What happens at boiling? When does it happen?
Boiling is a very fast form of evaporation that happens at every point pf a liquid. Boiling starts when the liquids vapor pressure is equal to the atmospheric pressure. Boiling only happens at a specific temperature though.
300
Explain what it is meant by 'Terminal Velocity' and how it works.
Terminal Velocity is the constant speed that an object free falling eventually reaches. When the object is falling, its air resistance starts to increase. Eventually, the air resistance overcomes the weight of the object and the object falls at a constant speed.
300
Describe the Energy Transformation when you throw a rock into the air and it falls back to the ground.
Chemical energy----->Kinetic energy----->Gravitational Potential Energy/Potential energy----->Kinetic energy----->Thermal energy+Sound energy(optional)
300
In science, what unit is temperature measured in? Explain what it is meant by absolute zero.
In science, temperatures are often measured using the Kelvin scale. The unit is kelvin (k). As the temperature falls, the particles in a material lose kinetic energy and move more and more slowly. At -273 Celsius, they cannot go slower. This is the lowest temperature there is, called absolute zero.
300
Explain how sweating contributes to the cooling effect of evaporation.
When your body temperature gets higher and you start to sweat, the sweat which is mainly water comes out of the pores in your skin. As it evaporates, it takes thermal energy away from your body and cools you down.
400
What is the difference between Mass and Weight? (3 examples)
Mass will always stay constant. Weight does not stay constant, it can be measured and will change depending where you are or what happened to you. Mass is how much "stuff" there is in an object. Weight is the measure of the gravitational pull on the earth. Mass is measured in Kg/g or (M) while Weight is measured in Newtons (N).
400
What is coal made from and why is it non renewable? What is bad about using coal?
Coal comes from the remains of plants and tiny sea creatures that lived millions of years ago. There is lots of energy inside them which is good as fuel for houses. However, there are limited supplies of coal in the world as it is non renewable. Burning coal is an irreversible change and releases CO2 in that pollutes the atmosphere. This contributes to global warming by increasing its global temperature and causing more natural disasters.
400
How do you find the lower fixed point (melting point) and the upper fixed point (boiling point) in a thermometer?
To find the lower fixed point, the unmarked thermometer must be put in pure, melting ice. The ice needs to be pure because its melting point is lower if its not pure. To find the upper fixed point, the thermometer must be in steam above boiling water. Boiling must be at atmospheric pressure because the boiling point will change if the pressure isn't the same.
400
Name the 4 factors that affect the rate of evaporation. State whether it increases or decreases the rate of evaporation.
1. Blowing air across the surface of a liquid. It increases the rate of evaporation. 2. High humidly decreases the rate of evaporation. 3. High temperature. It increases the rate of evaporation. 4. Increasing the surface area. It increases the rate of evaporation.
500
A car increases its velocity from 0 to 14 m/s in 6 secs. What is its average acceleration? State if its accelerating or decelerating.
+ 2.34 m/s(squared). Acceleration. Not deceleration.
500
An object has a mass of 8 kg. What is its gravitational potential energy if the object is 5m above the ground? (g=10 N/kg)
400 J
500
When pressure is constant, a balloon has a volume of 200cm(cubed) at 27 C. What is the volume of the balloon at 327 C? (To convert C into kelvins, use this... K= Celsius+273)
4 atm
500
Specific heat capacity- How much thermal energy is needed to raise 5 kg of water's temperature by 20 C? (water= 4200 J/Celsius kg)
420,000 J
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