1.4: The nature of energy
Which of the following statements about energy, work, and heat is true?
-energy can be classified into two fundamental forms: kinetic energy and potential energy -heat is energy transferred to increase the temperature of an object -work causes the displacement of an object -energy is the capacity to do work or transfer heat
As the distance between charges increase what happens to the magnitude of the charge
Decreases
Which change will lead to a larger change in the kinetic energy of an object, doubling its mass or doubling its speed?
Doubling its speed will increase the kinetic energy by a factor of four, while doubling its mass will only double the kinetic energy.
What is the formula for kinetic energy
Ek=1/2mv^2
Which of the following statements about energy, work, and heat is false?
Energy has mass and occupies space
Consider the following three vehicles in motion I. a compact car that weighs 2000 pounds and is traveling at 40 mph II.A medium sized car that weighs 3000 pounds and is traveling at 40 mph III. A truck that weighs 4000 pounds and is traveling at 20 mph Which of the following is the correct ordering of the vehicles from smallest to largest kinetic energy?
III<I<II
What are the two fundamental forms of energy
Kinetic energy and potential energy
What happens to the potential energy and kinetic energy as the bike rolls down the hill
The P.E decreased as it rolls down the hill, while at the same time the K.E increases as it picks up speed
What happens to the chemical energy of a lithium-ion battery as it is discharged to power a laptop computer? Does it increase, decrease, or remain unchanged?
The chemical potential energy of the battery decreases as it is discharged.
What is the chemical energy of a fuel due to?
The potential energy stored in the arrangements of atoms
T/F chemical energy is released when bonds between atoms are formed, and consumed when bonds between atoms are broken
True
T/F potential energy is stored energy that arises from the attractions and repulsion an object experiences in relation to to other objects
True
What is the difference between matter and energy?
Unlike matter, energy does not have mass and cannot be held in our hands, but it's effect can be observed and measured
Give an ig where P.E is converted into kinetic energy
a cyclist at the top of a hill. Because of the attractive force of gravity, The P.E of the bicycle is greater at the top of the hill than at the bottom. As a result, the bicycle easily rolls down the hill with increasing speed . As it does so, P.E is converted into K.E.
name some of the ways atoms and molecules can possess kinetic energy
although theses ptcls are too small to be seen they still have mass and are in motion. When a substance is heated, be it a pot of water on the stove or an aluminium can sitting in the sun, the atoms and molecules in that substance gain KE and their avg speed increases
Define force and give an ig
any push or pull exerted on the object ig: gravity and the attraction between poles of a bar magnet Note: It takes work to lift an object off of the floor, or to pull apart two magnets that have come together at the opposite poles
what is the most important forms of potential energy
electrostatic potential energy: which arises from the interactions between charged particles Forces that arise from electrical charges are more important.
Give one ig of the many substances that release energy when they react?
fuel
What arises from increased thermal energy?
increased molecular motion and hence increased kinetic energy at the molecular level
As the strength of an interaction increases what happens to the magnitude of the charge
increases
When we have a given velocity, kinetic energy increases with increasing or decreasing mass? ig
increasing mass Ig: a large truck traveling at 65 mi/hr (mph) has a greater kinetic energy than a motorcycle traveling at the same velocity because the truck has the greater mass
A rocket takes off from the surface of the earth and accelerates into the sky. which of the following correctly describes the changes in kinetic energy and potential energy due to gravity of the rocket as it takes off?
its K.E increases and its gravitational potential energy increase
What happens to the velocity/spped as the kinetic energy of an object increases. Give IG
its velocity or speed increases IG: For example, a car has greater kinetic energy moving 65 mph than it does 25 mph
What role do gravitational forces play in the ways that atoms and molecules interact with one another
negligable role
The magnitude of kinetic energy, Ek, of an object depend on what?
on its mass, m, and velocity, v
What occurs when a fuel burns?
some bonds are broken and others are formed, but the net effect is to convert chemical potential energy to thermal energy, the energy associated with temperature
Define energy
the capacity to do work or transfer heat
Define kinetic energy/ig
the energy of motion ig: objects, whether they are automobiles, soccer balls, or molecules
potential energy/ ig
the energy that an object possesses as a result of its positions with respect to another object Ig: the energy stored in a stretched spring, or in a weight held above your head, or in a chemical bond
Work
the energy transferred when a force exerted on an object causes a displacement of that object
heat
the energy used to cause the temperature of an object to increase
T/F K.E and P.E are incontrovertible
true
T/F Work is energy used to cause an object to move against an opposing force. Heat is energy used to increase the temperature of an object.
true
T/f the transfer of heat is simply the the transfer of K.E. at the molecular level
true
what is the formula for work
w=F x d w is the product of the force exerted on the object, F, and the distance, d, that it moves
