## **Work and power ** [b74cefbe9640] Results from the application of force over distance. When work is done, energy is transformed from one form to another. 1. **Work is only done if displacement occurs** (e.g., holding a weight without moving it does no work). 2. If **force and displacement **are in the **same direction**, work is** positive** (e.g., lifting a weight). 3. If **force and displacement **are in **opposite directions**, work is **negative **(e.g., lowering a weight). 4. **No work is done if the force is perpendicular to movement **(e.g., carrying a tray while walking forward). 5. Work is calculated using the formula: W = F x D 1. W = Work (Joules, J) 2. F = Force applied (Newtons, N) 3. d = Displacement of the object (meters, m) [{"_key":"dd106c734fff","_type":"block","asset":null,"children":[{"_key":"86a0d701b1040","_type":"span","marks":[],"text":"A weightlifter cleaning and jerking 100kg:"}],"markDefs":[],"style":"normal"},{"_key":"b124e46d4fb6","_type":"block","asset":null,"children":[{"_key":"7e72975312780","_type":"span","marks":[],"text":"Lifting phase: Positive work (against gravity)"}],"level":1,"listItem":"bullet","markDefs":[],"style":"normal"},{"_key":"cf0a2f417d0f","_type":"block","asset":null,"children":[{"_key":"96ee47efca270","_type":"span","marks":[],"text":"Holding overhead: No work (no displacement)"}],"level":1,"listItem":"bullet","markDefs":[],"style":"normal"},{"_key":"8fa9cb8a141e","_type":"block","asset":null,"children":[{"_key":"63bdcf5fdb4e0","_type":"span","marks":[],"text":"Lowering phase: Negative work (with gravity)"}],"level":1,"listItem":"bullet","markDefs":[],"style":"normal"},{"_key":"37c6825f37bd","_type":"block","asset":null,"children":[{"_key":"c619c96426ce","_type":"span","marks":[],"text":""}],"markDefs":[],"style":"normal"}] [{"_key":"6a41518d7bde","_type":"block","asset":null,"children":[{"_key":"0d7c51954e100","_type":"span","marks":[],"text":"Students often think that muscle fatigue means work is being done. Remember: without displacement, there's no work - even if you're tired from holding a position!"}],"markDefs":[],"style":"normal"}] [{"_key":"block_10","_type":"block","asset":null,"children":[{"_key":"pnOHAmVwEYlTc7rkSSpnsJ","_type":"span","markDefs":[],"marks":[],"text":"Work is only done when the force causes movement. Holding a weight stationary involves force but no work, as there is no displacement."}],"markDefs":[],"style":"normal"}] ## [075e0c67d53f] Power is **the amount of energy transferred or converted per unit time. **It is given by the formula: **P=ΔW/Δt **where **ΔW** = change in work done and **Δt** = change in time 1. **Power combines:** 1. Force application 2. Velocity of movement 3. Timing and technique 2. **Key Factors Affecting Power:** 1. Force applied: More force increases power output. 2. Speed of movement: Faster execution of a movement increases power. 3. **Power in Sport:** 1. Explosive movements (high power output): Sprinting, weightlifting, and jumping. 2. Sustained power (lower but continuous output): Distance running, swimming, and cycling. 3. Power is crucial in sports that require bursts of strength, such as shot put and high jump. [{"_key":"19a3e9956f48","_type":"block","asset":null,"children":[{"_key":"e831d397e58e0","_type":"span","marks":[],"text":"To improve power output, focus on both force (strength) and velocity (speed). Improving either component will increase power, but optimizing both gives the best results."}],"markDefs":[],"style":"normal"}] ### Optimizing Power Output [b54334bd411a] 1. **Through technique: ** 1. Proper biomechanics 2. Efficient movement patterns 3. Optimal force application 4. Minimizing energy waste 2. **Through equipment: ** 1. Proper sizing and fit 2. Material selection 3. Design efficiency 4. Regular maintenance [{"_key":"20ce7d7a48a1","_type":"block","asset":null,"children":[{"_key":"b2f9b03052210","_type":"span","marks":[],"text":"Power output isn't just about maximum effort - it's about optimal effort. Sometimes, reducing force but increasing speed produces better power output."}],"markDefs":[],"style":"normal"}] ### Practical Applications [01255f1513bb] 1. **In explosive movements: ** 1. Jumping (vertical power) 2. Throwing (rotational power) 3. Sprinting (horizontal power) 2. **In sustained activities: ** 1. Cycling (continuous power) 2. Swimming (rhythmic power) 3. Running (endurance power) [{"_key":"0356122522d5","_type":"block","asset":null,"children":[{"_key":"0bed07251ed00","_type":"span","marks":[],"text":"How does our understanding of work and power challenge traditional training methods? Consider how scientific knowledge has transformed athletic preparation and performance."}],"markDefs":[],"style":"normal"},{"_key":"8ecdac84b6c5","_type":"block","asset":null,"children":[{"_key":"a46dec198ac20","_type":"span","marks":[],"text":""}],"markDefs":[],"style":"normal"}] ## Energy [3b27c317af1f] **The ability to do work, which is the ability to exert a force causing displacement of an object**. ### Types of Mechanical Energy: [b6460e994c66] 1. **Kinetic Energy (Energy of Motion):** 1. Depends on mass and speed. 2. Increases with higher velocity (e.g., a fast-moving soccer ball has more kinetic energy than a slow one). 2. **Potential Energy (Stored Energy):** 1. Exists due to an object’s position or condition. 2. A higher position increases stored energy (e.g., a diver on a high platform has more potential energy than one on a low board). 3. **Elastic Potential Energy:** 1. Stored in objects that can stretch or compress, such as springs, rubber bands, or muscle tendons. 2. Important in movements like jumping, where energy is stored and released. **4. Energy Transformation in Sport:** 1. A pole vaulter converts potential energy into kinetic energy during takeoff. 2. A basketball player jumps by converting stored energy in leg muscles into motion energy. ## The relationship between work, energy, and power [6680b5569098] 1. **Work** is needed to change an object’s energy. 2. **Energy** allows an athlete to perform work. 3. **Power** determines how quickly an athlete can use energy to perform work. **Sport-Specific Examples:** 1. A cyclist generates **power** by continuously applying force to the pedals. 2. A soccer player uses kinetic **energy** to strike a ball, transferring energy to it. 3. A gymnast performing a flip converts stored energy into movement **energy**. ![](https://cdn.sanity.io/images/w7j7fz60/production/230833c10ebcef8bb8a959beacb63e657377e340-1456x1017.jpg) ## Energy transformations in work [block_11] 1. **Energy** is the capacity to do work, and it exists in various forms: 2. **Kinetic Energy**: Energy of motion (e.g., a sprinter accelerating). 3. **Potential Energy**: Stored energy due to position (e.g., a diver at the top of a platform). 4. **Chemical Energy**: Stored in muscles and converted to mechanical energy during movement. 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