6.1.1 The Nature of Energy

Question 1

The Nature of Energy

Answer 1

Kinetic energy (KE) is energy of motion; potential energy (PE) is stored energy; internal energy (E) is kinetic energy
plus potential energy.
• Thermochemistry is the study of energy changes for a chemical system.
- E = 1/2mv^2
- 1J = 1kg*m^2/s^2

Question 2

note

Answer 2

• Energy is the capacity to do work or transfer heat.
• Kinetic energy (KE) is the energy associated with particles in motion.
• Potential energy (PE) is stored energy, or the energy inherent in a system at a particular state.
• The system is the portion of the universe under study. The surroundings are the rest of the universe.
• Internal energy (E) is the sum of the kinetic energy and the potential energy of a system.
• Thermochemistry is the study of energy changes for a chemical system. For example, the breaking of bonds and the excitation of electrons involve changes in energy.
• The change in internal energy for a system is denoted E. The change in internal energy is equal to the final energy (E f ) minus the initial energy (E i ).
• Work (w) and heat (q) are two general ways for a system to exchange energy with the surroundings.
• Work is measured in joules (J). Examples of work include lifting (w = F · d, where F is the gravitational force) and separating socks (w = F · d, where F is the Coulomb force).
• Heat is measured in calories (cal). A calorie is the amount of heat required to heat 1 g of water from 14.5 ̊C to 15.5 ̊C. 1 cal = 4.184 J.
• Work can be converted to heat. For example, if you beat a metal pole with a hammer, the pole becomes warm.

Question 3

What is the potential energy of a 7.00 kg bowling ball that is on a shelf that is 2.50 m high?

Answer 3

172 J

Question 4

What is the most common unit used in measuring heat?

Answer 4

calorie

Question 5

How many joules is 677.0 calories equal to?

Answer 5

2833 J

Question 6

If an object has a kinetic energy of 27 J and a velocity of 6.0 m / s, what is the mass of the object?

Answer 6

1.5 kg

Question 7

Which of the following objects has non-zero potential energy, but zero kinetic energy?

Answer 7

An encyclopedia on the top shelf of a bookcase

Question 8

What is the kinetic energy of a basketball having a mass of 0.65 kg that is falling at 3.5 m / s?

Answer 8

4.0 J

Question 9

Which of the following is not a form of energy?

Answer 9

voltage

Question 10

How many calories are in 299.5 J?

Answer 10

71.58 cal

Question 11

Which of the following steps illustrates work being done?

Answer 11

A box being pushed up a ramp.

Question 12

What is the SI unit for energy?

Answer 12

joule