Daily Science pg. 40 - PowerPoint PPT Presentation

About This Presentation
Title:

Daily Science pg. 40

Description:

Daily Science pg. 40 Convert the following temperatures: 45oC into Kelvin 45o C into Fahrenheit 309 K into Fahrenheit 98oF into Kelvin 299 K into Celsius – PowerPoint PPT presentation

Number of Views:35
Avg rating:3.0/5.0
Slides: 9
Provided by: Dista67
Category:

less

Transcript and Presenter's Notes

Title: Daily Science pg. 40


1
Daily Science pg. 40
  • Convert the following temperatures
  • 45oC into Kelvin
  • 45o C into Fahrenheit
  • 309 K into Fahrenheit
  • 98oF into Kelvin
  • 299 K into Celsius
  • 8oF into Kelvin
  • Give an example of conduction, convection, and
    radiation. Explain why over exposure to the sun
    or to X-rays can be harmful.
  • Calculate the kinetic energy of a wheel that has
    a mass of 65 kg and is rolling with a velocity of
    4.5 m/s.
  • Calculate the potential energy of a bomb that is
    falling from a height of 48 m and has a mass of
    15 kg.
  • Calculate the potential energy of a ball dropped
    from E-wing that weighs 4.8 N and is being
    dropped 6 m.
  • Calculate the mass of a person in a wheelchair if
    they are rolling at a velocity of 0.7 m/s and
    have 20 j of kinetic energy.

2
Specific Heat
  • Pg. 41

3
Conductors and insulators
  • Conductor- a material through which energy can be
    transferred as heat.
  • Examples
  • Insulator- a material that transfers energy
    poorly.
  • Examples

4
Specific Heat
  • The amount of energy needed to change the
    temperature of a substance by a certain amount is
    what determines if a substance will be a good or
    poor conductor.
  • Specific heat is the quantity of heat needed to
    raise the temperature of 1 kg of substance by 1
    K.
  • Specific heat is a physical property.

5
Specific heat values
  • Every substance has a unique specific heat.
  • The letter C is used to denote specific heat.
  • Water has one of the highest specific heat values
    (4,186 J/kg x K)

6
Calculating Specific Heat
  • Heat mass x temperature change x specific heat
    value
  • Q m x ?T x C
  • Units
  • Mass-
  • Temperature-
  • Specific Heat-
  • Heat-

7
Practice Problems
  • How much energy is needed to increase the
    temperature of 0.755 kg of iron from 283 K to 403
    K?
  • How much energy must a refrigerator absorb from
    225 g of water to decrease the temperature of the
    water from 35oC to 5oC?

8
State changes
  • Heat makes objects change state.
  • Energy of a substance either raises the
    substances temperature or changes the
    substances state. NOT BOTH AT THE SAME TIME.
  • This is why there
  • are horizontal lines
  • on a phase change
  • diagram.
Write a Comment
User Comments (0)
About PowerShow.com