Energy Study Guide
The different molecules that make up the air in a room have, on average, the same kinetic energy. How does the speed of the different air molecules depend on their masses?
If mixed together, molecules with various masses will move at different speeds related to their mass.
A boulder on top of a cliff has potential energy of 8800 J and twice the mass of a boulder next to it, What is the GPE of the smaller boulder?
If the boulder has 1/2 the mass, then it has 1/2 the potential energy, so the answer is 4,400 J.
What is energy?
The ability to do work or cause change
The different molecules that make up the air in a room have, on average, the same kinetic energy. How does the speed of the different air molecules depend on their masses?
they will move at differnet speed depending on there mass.
What are two examples of potential energy?
1. a ball on the top of a hill( if it isn't moving) 2. a book on a shelf ( if it isn't moving)
The potential energy of a swig is 200 J at its highest point and 50 J at its lowest point. If the mechanical energy is conserved, what is the kinetic energy of the swing at its lowest point?
200 J (200=PE+KE). 200=50+KE KE=150
The mechanical energy of a bicycle at the top of a hill is 6000 J. The bicycle stops at the bottom of the by applying the brakes. If the potential energy of the bicycle is 2000 J at the bottom of the hill, how much thermal energy was produced?
6000 - 2000 = 4000 J
What is a joule?
A unit of energy
Can an object have kinetic energy and potential energy at the same time?
An object can have both kinetic and potential energy at the same time. For example, an object which is falling, but has not yet reached the ground has kinetic energy because it is moving downwards, and potential energy because it is able to move downwards even further than it already has.
What are three situations in which the gravitational potential energy of an object changes
An object is raised higher, an object falls to a lower height or a mass of an object above Earth's surface.
What are the four kinds of energy?
Electrical Chemical Radiant Thermal
what is chemical potential energy?
Energy stored in chemical bonds
Fission and fusion are nuclear reactions that change small amounts
Explain how energy is conserved when nuclear fission or fusion occurs.
Explain how friction affects the mechanical energy of a system
Friction decreases the kinetic energy which decreases the mechanical energy.
Explain how energy is conserved when nuclear fission or fusion occurs.
Fission and fusion are nuclear reactions that change small amounts to large amounts
Explain how energy is conserved when nuclear fission or fusion occurs.
Fission and fusion are nuclear reactions that convert a small amount of mass in a nucleus into an enormous amount of energy.
Describe the energy transformations that occur as you coast down a long hill o a bicycle and apply the brakes, causing that brake pads and bicycle rims to feel warm.
Friction converts kinetic energy into heat. That's what friction does. If friction didn't create heat, you wouldn't be able to stop.
Describe the energy transformations that occur as you coast down a long hill o a bicycle and apply the brakes, causing that brake pads and bicycle rims to feel warm.
Friction converts kinetic energy into thermal energy.
Explain how friction affects the mechanical energy of a system
Friction decreases it.
A roller coaster is at the top of a hill and rolls to the top of a lower hill. If the mechanical energy is conserved, on the top of which hill is the kinetic energy of the roller coaster larger?
If the mechanical energy is conserved then there is no friction, Therefore it would just decrease speed with more height. Therefore, the speed is greater at the top of the lower hill, and therefore the kinetic energy as well.
How do you calculate kinetic energy?
K=1/2 mv^2
Find the kinetic energy of a ball with a mass of 0.06 kg moving at 50 m/s.
KE = 1/2 (0.06) (50^2) = 75 kgm^2/s^2 = 75 joules
How are potential and kinetic energy related?
Kinetic energy is a form of energy that results from an object's motion. The measurement of kinetic energy in an object is calculated based on the object's mass and velocity. It is measured in Joules. Potential energy is a form of energy that results from an object's position or arrangement of parts. It is stored energy that can become kinetic energy. The measurement of potential energy in an object is calculated based on the object's mass and its height or distance. It is measured in Joules.
How does height and mass effect GPE?
The higher up an object is the greater its gravitational potential energy. The more mass an object has the more gravitational potential energy it has.
Explain how the kinetic energy of a truck could be increased without increasing the truck's speed
The kinetic energy could increase if the mass increases.
What is elastic potential energy?
The potential energy of an object that is stretched or compressed
What is GPE?
mgh (mass, acceleration due to gravity, and height)