Energy 1
Define energy
the ability to do work
This is the abbreviation for kinetic energy.
K.E
Energy possessed by a drop of water about to fall from the top of a waterfall.
Potential energy
How much work is done by gravity when a 5 kg object falls 10 m to the ground?
490 J
energy in motion
kinetic energy
Energy can not be lost or destroyed, only transformed into a different form of energy. True or False
True
Potential energy associated with objects that can be compressed.
Elastic potential energy
How much work is done on a 1000 kg car that is slowed to a stop by a frictional force of 400 N over a 50 m distance?
W = Fd = (-400)(50) = -20,000 J
SI unit of potential energy
joules
What is the energy transformation when you rub your hands together
kinetic/mechanical to thermal
True or false: Energy is anything that has mass and takes up space.
False. The answer is matter.
A50 kg child has a KE of 100 J when she runs at what speed?
2 m/s
Define Nuclear Energy
Energy stored in the nucleus of an atom.
Factors that potential energy depends on
mass, height, gravitational constant
To calculate mechanical energy of a body what all must you add?
Its potential energy and kinetic energy
A 5 kg object at a height of 10 m that is falling at 4 m/s has a Total Energy (E) of
530 J
Type(s) of energy used by an oven use to bake cakes.
Electric energy and heat energy
A hair dryer transforms _______energy to _____ and ________
electrical, heat and sound
This is the broader category gravitational energy is a part of.
Potential energy
A 1600 kg car is travelling at 14 m/s when it crashes into a brick wall, stopping over a distance of 0.5 m.
a. How much work is done by the wall during the crash?
b. What force is applied during the crash?
a. 156,800 J b. 313600 N
The sum of potential and kinetic energy of an object.
Mechanical Energy
If you were to fall, this would increase as you fell.
kinetic energy
If you have a bowling ball, basketball, and a tennis ball moving in the same speed, which ball have more kinetic energy? Why?
Bowling ball - it has more mass.
A force of 4.7 N is required to stretch a certain spring by 1.3 cm. How far must this spring be stretched for its potential energy to be 0.02 J?
0.011 m or 1.1 cm
When an object's _____ doubles, its ........... energy quadruples.
speed, kinetic
A small plane tows a glider. If the plane does 2 x10^5 J of work to tow the glider 145m with a pull force of 2560 N, what is the angle between the tow rope and the horizontal?
57.4 degrees
If there is friction between 2 moving bodies, then mechanical energy is converted into............
heat
A 0.26 kg rock is thrown vertically upward from the ntop of a cliff that is 32 m high. When it hits the ground ath the base of the cliff the rock has a speed of 29 m/s. Find the initial speed of the rock.
15 m/s