Work, Energy, Power and doppler

Question 1

State the work-energy theorem (Wnet = ΔK = Kf - K)

Answer 1

The work done on an object by a net force is equal to the change in the object’s kinetic energy OR the work done on an object by a net force is equal to the change in the object’s kinetic energy

Question 2

Conservative force

Answer 2

A force for which the work done in moving an object between two points is independent of the path taken (Examples are gravitational force, the elastic force in a spring and electrostatic forces (coulombic forces).)

Question 3

non-conservative force

Answer 3

A force for which the work done in moving an object

between two points depends on the path taken.

Question 4

State the principle of conservation of mechanical energy

Answer 4

The total mechanical energy (sum of gravitational potential energy and kinetic energy) in an isolated system remains constant.

Question 5

Power (p=W/Δt)

Answer 5

The rate at which work is done or energy is expended.

Question 6

Doppler effect

Answer 6

The change in frequency (or pitch) of the sound detected by a listener, because the sound source and the listener have different velocities relative to the medium of sound propagation.

Question 7

State applications of the Doppler effect

Answer 7

Measuring the rate of blood flow, or heart beat of unborn babies using ultra sound
Radar guns to measure the speed of cars