work power energy

Question 1

work done is?

Answer 1

integration from A to B of F.ds

Question 2

what does this ds depend on

Answer 2

it does not depend on force applied. it may or may not be caused by the force

Question 3

what is the exact definition of work done

Answer 3

force*(displacement caused at the point of application)

Question 4

if body moves in a curvillinear path and F is constant

Answer 4

W=F.s

Question 5

work done in circular motion

Answer 5

0

Question 6

work done by gravity is

Answer 6

mgh from moving up to down

-mgh from moving down to up

Question 7

work_total=

Answer 7

integration of f_net.ds

Question 8

total work done by all forces is

Answer 8

work done by net force

Question 9

work done by variable force is

Answer 9

integration of (fxi+fyj+fzk).(dxi+dyj+dzk)

Question 10

if force acts in only x direction

Answer 10

displacement is only in x axis and W=integration(Fxdx)

Question 11

if F=f(x)

Answer 11

W=integration of f(x)dx from x1 to x2

Question 12

work done by spring force

Answer 12

1/2kx1^2-1/2kx2^2

Question 13

what are the limits of integration in compression

Answer 13

from 0 to -x

Question 14

work done in a different frame of reference

Answer 14

integration of F.ds(in the frame of reference)

Question 15

total work done by all forces

Answer 15

total change in kinetic energy

Question 16

if 2 different springs (not attached to each other) is acting on a body

Answer 16

k_equivalent=k1+k2

Question 17

if 2 different springs (attached to each other) is acting on a body

Answer 17

1/k_eq=1/k1+1/k2

Question 18

what is the work done by a system of bodies

Answer 18

total change in kinetic energy of system of bodies

Question 19

what is a conservative force

Answer 19

work done is independent of path and only depends on initial and final points

Question 20

what is a non-conservative force

Answer 20

work done is dependent of path

Question 21

what is potential energy

Answer 21

energy possessed by virtue of position

Question 22

when does potential energy change

Answer 22

only when conservative force does work

Question 23

formula of potential energy

Answer 23

-(work done by conservative force)

Question 24

where is the potential energy 0

Answer 24

the potential energy is 0 at the reference point

Question 25

whAT IS principle of conservation of mechanical energy

Answer 25

Uf+KEf=Ui+KEi

Question 26

what is mechanical energy

Answer 26

U+KE

Question 27

what is work done by non conservative and external forces

Answer 27

change in mechanical energy

Question 28

how to find fx fy and fz

Answer 28

partially differentiate U wrt dx dy and dz respectively

Question 29

eg if U=3x^2yz find fx,fy and fz

Answer 29

fx=6xyz
fy=3x^2z
fz=3x^2y

Question 30

whats stable equilibrium

Answer 30

its a position where the body shows tendency to the equilibrium upon being disturbed from equilibrium

Question 31

whats unstable equilibrium

Answer 31

equilibrium position where the body shows tendency to move away from equilibrium upon being disturbed

Question 32

whats neutral equilibrium

Answer 32

equilibrium which is neither stable nor unstable

Question 33

at stABLE EQUILIBRIUM

Answer 33

PE IS MINIMUM

Question 34

at unstable equilibrium

Answer 34

PE is maximum

Question 35

how do you get to know if a body is in stable or unstable equlilbrium

Answer 35

dU/dx=0

Question 36

how to represent stable unstable and neutral equilibrium on graph

Answer 36

local minimum is stable equilibrium
local maxima is unstable equiibrium
a straight line represents neutral equilibrium

Question 37

what is power

Answer 37

rate of doing work

Question 38

average power

Answer 38

work done/time interval

Question 39

instantaneous power

Answer 39

dW/dt

F.v

Question 40

total of average powers due to all forces on a body

Answer 40

change in ke by time

Question 41

total of instantaneous powers due to all forces on a body

Answer 41

d(ke)/dt