Energy
Energy stored in coal is called
chemical energy
Work transfers what?
Energy
Work math problems' answers are always in what unit of measure
Joules
Machines can be 100% efficeient. True or False
False
Machines always lose some work input due to friction
define elastic potential energy
an object that can be stretched or compressed
If an object is becoming warmer, what type of energy is increasing?
THermal energy
a)Is work done if lift a rock? b)What if I lift it and start to walk?
a) Yes B) no
Give the formula for ideal mechanical advantage
IMA= Input distance/Output distance
Power of a machine measures the force it produces. True or False
False
It measures the rate of doing work
Law of Conservation of Energy has 3 principles. Name tham
Energy can't be created
Energy can't be destroyed
Energy can be converted from one form to another
Energy of motion is called
Kinetic energy
If the force on an object is not in the direction of the object's motion, is work done?
no
If I move a china cabinet acroos the room at 150 N for a distance of 4.0 m and it takes me 2 minutes, what is my power?
2 min 60 sec
_____ x _____ = 120 sec
1 1 min
150 N x 4.0 m
___________ = 5 W
120 sec
a hammer is an example of what simple machine
lever
Power math problems' answers are always in what unit of measure
Watt
Energy stored as position or shape is called
Potential energy
If I move a sofa across the floor a distance of 3.0 m at a constant force of 130 N, how much work am I doing?
130 N x 3 m= 390 Joules
Man is riding his motorbike at a speed 60m/s and he weighs 83 kg. What is the kinetic energy?
0.5 x 83 kg x (60 m/s)2 =
0.5 x 83 x 3600=149,400 Joules
In an inclined plane, what is the input distance and the output distance?
Input distance is the ramp or slope of the plane. THe ouput distance is the height of the plane.
If friction were removed from the equation of work, how would it effect AMA?
It would increase
Energy that depends on mass, accelearation of gravity, and height relative to a reference level is called
Gravitational potential energy
A screwdriver is an example of what kind of simple machine
Wheel and axle
A frog that weighs 0.36 kg jumps off of a tree that is 1.6 m high. What is the potential energy of the squirrel in the tree?
0.36 kg x 9.8 m/s2 x 1.6 m =5.64 Joules
What is the formula for Power? Name two.
P= W/t
P= F x d
_____
t
How does a machine make work easier? List 2 ways
1) increases or magnifies the force you apply
2) changes the direction of the force