Introduction

In dynamics, we found a relationship between "impulse" and "momentum" as well as "work" and "kinetic energy". We'll explore these ideas further.

We'll introduce the concept of conservation of momentum and its application.

We'll relate kinetic energy to other forms of energy and introduce the concept of "conservation of energy" and we'll look at energy use over time (power) as well as the concept of "efficiency".

Relevant dot points from the Study Design

• analyse impulse (momentum transfer) in an isolated system (for collisions between objects moving in a straight line): ${\displaystyle I=\Delta p}$
• investigate and analyse theoretically and practically momentum conservation in one dimension.
• apply the concept of work done by a constant force using:
  • work done = constant force ${\displaystyle \times }$ distance moved in direction of force: ${\displaystyle W=Fs}$
  • work done = area under force-distance graph
• investigate and analyse theoretically and practically Hooke’s Law for an ideal spring: ${\displaystyle F=-k\Delta x}$
• analyse and model mechanical energy transfers and transformations using energy conservation:
  • changes in gravitational potential energy near Earth’s surface: ${\displaystyle E_{g}=mg\Delta h}$
  • potential energy in ideal springs: ${\displaystyle E_{s}={\tfrac {1}{2}}k\Delta x^{2}}$
  • kinetic energy: ${\displaystyle E_{k}={\tfrac {1}{2}}mv^{2}}$
• analyse rate of energy transfer using power: ${\displaystyle P={\frac {E}{t}}}$
• calculate the efficiency of an energy transfer system: ${\displaystyle \eta ={\frac {\text{useful energy out}}{\text{total energy in}}}}$