5. Work, energy and power

Question 1

work

Answer 1

D- product of force and displacement in direction of force.

E-work done = force × displacement in the direction of the force. W=Fs

Question 2

principle of conservation of energy //

Question 3

efficiency of a system and use the concept of efficiency to solve problems

Answer 3

ratio of useful energy output from the system to the total energy input.

ratio of useful power output from the system to the total power input.

for percentage %- multiply by 100

Question 4

derive P = Fv

Answer 4

power= force * velocity
velocity= displacement/time. v=s/t

P=W/t
P=(F*s)/t
P=Fv

Question 4

power

Answer 4

work done per unit time. P = W/t
energy transferred per unit time. P=E/t

Question 5

derive G.P.E

Answer 5

gravitational potential energy changes in a uniform gravitational field= massgravitychange in height

W=Fs W=mg
g=acceleration of free fall

∆Ep = mg∆h

Question 6

derive K.E ///

Answer 6

EK = 1/2mv^2