What is Work in Science? Grade 7 Physics Definition and Examples

📚 Quick Study Guide

🔍 Work is done when a force causes an object to move a certain distance. 💡 The formula for work is: $W = F \cdot d$, where:
• $W$ = Work (measured in Joules, J)
• $F$ = Force (measured in Newtons, N)
• $d$ = Distance (measured in meters, m)
📝 Work is only done if the force and the displacement are in the same direction. If you push against a wall and it doesn't move, you're not doing work (in the physics sense!). ➕ Positive work means energy is being added to the object (speeding it up or lifting it). Negative work means energy is being taken away (slowing it down). 🏋️ Examples of work: Lifting a box, pushing a shopping cart, or a car engine moving the car. 🚫 Examples of NO work: Holding a heavy object stationary, gravity acting on a planet in a circular orbit (force is perpendicular to motion).

🧪 Practice Quiz

1. What is the definition of work in physics?
   1. Applying force to an object.
   2. Moving an object.
   3. Applying a force to an object and causing it to move.
   4. Thinking hard about moving an object.
2. The formula for calculating work is:
   1. $W = m \cdot g$
   2. $W = F \cdot d$
   3. $W = \frac{F}{d}$
   4. $W = m \cdot v$
3. What unit is work measured in?
   1. Newtons (N)
   2. Meters (m)
   3. Joules (J)
   4. Kilograms (kg)
4. Which of the following is an example of work being done?
   1. Holding a book.
   2. Pushing a car that doesn't move.
   3. Lifting a box.
   4. Sitting in a chair.
5. If you apply a force of 10 N to move a box 2 meters, how much work have you done?
   1. 5 J
   2. 8 J
   3. 12 J
   4. 20 J
6. What does it mean when work is negative?
   1. Energy is being added to the object.
   2. Energy is being taken away from the object.
   3. No force is being applied.
   4. The object is moving at a constant speed.
7. In which scenario is no work being done (in the physics sense)?
   1. A rocket launching into space.
   2. A ball rolling down a hill.
   3. Holding a heavy backpack stationary.
   4. Pulling a sled across the snow.