chapter 6 energy work and power

Question 1

energy

Answer 1

capacity to do work
unit: J

Question 2

kinetic energy

Answer 2

energy of a body due to its motion
KE = 1/2mv^2 (m = mass, v = speed)

Question 3

potential energy

Answer 3

stored energy in a system

Question 4

chemical potential energy

Answer 4

energy stored in a substance due to the position of the atoms or electrons in the substance

Question 5

elastic potential energy

Answer 5

energy stored in a body due to its elastic deformation

Question 6

gravitational potential energy

Answer 6

energy stored in a body due to its height from the ground

GPE = mgh (m = mass, g = gravitational field strength in ms^-2, h = height)

Question 7

principle of conservation of energy

Answer 7

energy cannot be created or destroyed but can be converted from one form to another
total energy in isolated system is constant

Question 8

efficiency

Answer 8

useful energy output/total energy output x 100%

Question 9

work done (by constant force on an object)

Answer 9

product of the force and the distance moved by the object in the direction of the force

work done = energy transformed

W = F x s
(W = work done by constant force in J, F = constant force in N, s = distance moved by the object in direction of force in m)

Question 10

power

Answer 10

rate of work done

P = W/t = E/t (P = power in W, W = work done in J, t = time in SECONDS)