WORK, POWER, ENERGY Flashcards
define work
when a force is applied on a body and it covers some displacement in the direction of force.
at which angle, work done is zero
at 90°
at which angle is work done maximum and positive
0°
at which angle is work done half of the maximum value
60°
at which angle is work done maximum and negative
180°
what are the SI units of work
joule
base units of work
Nm or kgm^2/s^2
for conservative field, work done along closed path is
zero
1 J is equal to how many ergs
10^7
what is the CGS unit of work
erg
for cyclic Fd graph, work done will be
0
give examples of conservative fields
gravitational field, electric field, magnetic field, elastic field and nuclear force
for non-conservative field, work done along closed path is
not zero
give examples of non-conservative field
frictional force, drag force, air resistance, tension and normal reaction
define energy
ability of body to do work
formula for potential energy
P.E = mgh
formula for absolute potential energy
P.E = -GMm/R
formula for kinetic energy
1/2mv^2
formula for elastic potential energy
1/2kx^2
potential energy if movement is upwards will be
-mgh
potential energy if movement is downward will be
+mgh
negative P.E means
increasing potential energy
positive P.E means
decreasing P.E
in the presence of air resistance, what will be the formula relating P.E & K.E if movement is upward
K.E = P.E + Wf
1/2mv^2 = mgh + hf
