Energy (Part 1)

Question 1

What is the law of conservation of energy?

Answer 1

Energy cannot be created nor destroyed it can only be transferred or transformed

Question 2

List various forms of energy

Answer 2

• Thermal
• Radiant
• Sound
• Kinetic
• Mechanic
• Nuclear fission
• Electrical
• Chemical
• Solar

Question 3

You operate a toaster, what form of energy is going in?

Answer 3

Electrical

Question 4

You operate a toaster, what form of energy is coming out?

Answer 4

Thermal
Radiant
Mechanical
Sound

Question 5

You operate a toaster, what form of energy is dissipated energy?

Answer 5

Radiant

Sound

Question 6

You operate a toaster, what form of energy is useful?

Answer 6

Thermal

Question 7

If to wash your clothes your washing machine requires 15KJ but your machine consumes 20KJ what is the energy efficiency of the machine?

Answer 7

75% useful

25% dissipated

Question 8

If your car system only uses 12% of the chemical energy from gasoline to actually make the car move, and you know that the energy required to move the 1000kg car at a speed of 100km/h is 250KJ, how much energy is dissipated?

Answer 8

2083.33KJ dissipated

Question 9

A motor with an energy efficiency of 80% consumed 360 000J of electrical energy. While it was in operation, 72 000J of the energy were dissipated in the form of sound and heat?

Answer 9

288 000J

Question 10

Describe temperature vs heat

Answer 10

Temperature: Measurement of the energy/particles in a substance
Heat: Energy/moving particles in a substance. Can be transferred or transformed.

Question 11

Describe thermal energy. vs heat

Answer 11

Thermal energy:

Heat:

Question 12

If heat/KJ is written in the products of a reaction is it endo or exo?

Answer 12

Exothermic

Question 13

If heat/KJ is written in the reactants of a reaction is it endo or exo?

Answer 13

Endothermic

Question 14

When is Q negative?

Answer 14

When it is exothermic

there is a loss of heat

Question 15

When is Q positive?

Answer 15

When it is endothermic

gain heat

Question 16

Describe each variable in solving for Q

Answer 16

Q= change in heat (joules)
m= mass (g)
c= specific heat capacity
delta t= change in temperature (C) (tf-ti)

Question 17

If 100g of H2O are heated from 20 C to 44 C, calculate the thermal energy produced.

heat capacity=4.184

Answer 17

Q=10041.60 J

Question 18

20KJ thermal energy was added by heating 200g of vegetable oil for french fries and you started with oild at 25 C how how did the oil get while cooking?

Answer 18

75 C