We delve into the fascinating world of simple machines, exploring how the ancient Egyptians utilized these principles to construct the pyramids. Building on this foundational knowledge, we will examine potential and kinetic energy, define momentum and recoil as observed in springs, and investigate the differences between elastic and inelastic collisions.
We will explore ancient Egyptian engineering, delve into the principles of potential and kinetic energy, and understand momentum and recoil through various examples. You will participate in a discussion board, complete critical thinking assignments, and solve motion problems relevant to astronauts aboard the International Space Station.
Learning Outcomes
- Understand simple machines, work, and power.
- Contrast potential and kinetic energy.
- Describe momentum and recoil.
- Discuss elastic and inelastic collisions.
1. Simple Machines, Work, and Power
Simple machines, known for their force multiplication and redirection capabilities, are essential tools in physics. They help users perform work more easily by allowing the exchange of longer distances for lower force. Work is defined as Force x Distance.
The six basic simple machines are:
- Lever
- Wheel and axle
- Inclined plane
- Wedge
- Pulley
- Screw
Mitts (2012) introduces the foil as the seventh simple machine, citing airplane wings and boat propellers as examples that convert mechanical energy to fluid energy and vice versa.
Power, the rate at which work is performed, is measured in watts (Joules per second). A motor’s power rating indicates the rate at which it can perform work.
2. Potential and Kinetic Energy
Energy expended by a force over a distance results in kinetic energy when it moves an object. Conversely, potential energy is stored when kinetic energy is used to lift or stretch an object. In real-world scenarios, some energy is lost as heat and light due to frictional forces.
Examples of potential energy conversion include:
- Swinging pendulums
- Stretched springs
- Drawn bows
3. Momentum and Recoil
Momentum, a vector quantity defined as mass multiplied by velocity, plays a crucial role in understanding collisions. Momentum is conserved in isolated systems, meaning the total momentum before and after a collision remains constant. Recoil occurs when objects push against each other and move in opposite directions. The conservation of momentum ensures that the total momentum of recoiling objects sums to zero.
4. Elastic and Inelastic Collisions
Elastic collisions preserve kinetic energy, whereas inelastic collisions do not. Inelastic collisions result in some kinetic energy being converted to other forms like heat and sound. When objects stick together post-collision, their combined mass influences their subsequent velocity.
References
- Diffen (n.d.) Energy vs. power. Retrieved from http://www.diffen.com/difference/Energy_vs_Power
- Idaho Public Television. Simple machines: Facts. Science Trek. Retrieved from http://idahoptv.org/sciencetrek/topics/simple_machines/facts.cfm
- Mitts, C. R. (2012). The fluid foil: The seventh simple machine. Technology and Engineering Teacher, 71(6), 7-12.
