Year 9 Science · Unit 3 · Lesson 6
Foundation Worksheet
Learning Goals
Match each term to its meaning
Write the letter of the matching meaning in the middle column. Each letter is used once.
| Term | Letter | Meaning |
|---|---|---|
| Work | A. The unit of power: 1 of these is 1 joule per second | |
| Power | B. How far an object moves in the direction of the force, in metres | |
| Joule | C. The energy transferred when a force moves an object in the direction of the force | |
| Watt | D. The unit of force: gravity pulls on each 1 kg with a force of about 10 of these | |
| Newton | E. The rate at which work is done, or energy is transferred | |
| Distance | F. The unit of work and energy, equal to 1 newton-metre |
1. In science, what TWO things must happen for a force to do work on an object?
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
A 100 W globe transfers 100 joules of electrical energy every second.
Correct it:
A more powerful machine always does more total work than a less powerful one.
Correct it:
Pushing against a brick wall with all your strength does scientific work on the wall.
Correct it:
One joule of work is done when a force of 1 N moves an object 1 m in the direction of the force.
Correct it:
When you carry a schoolbag along a flat corridor at a steady height, your upward force on the bag does work on it.
Correct it:
Sort it: work or no work?
Write each example in the correct box. Ask yourself: does the object move in the direction of the force?
Work is done on the object
No work is done on the object
2. A gardener pushes a wheelbarrow of mulch along a flat path with a steady forward force of 80 N. The wheelbarrow moves 25 m. Calculate the work done by the gardener on the wheelbarrow. Show your working.
Work done J
3. A student lifts a 12 kg box of books from the floor onto a shelf 1.5 m high. Use g = 10 N/kg, so the weight of an object in newtons is its mass in kilograms × 10. Calculate (a) the weight of the box and (b) the work done lifting it.
(a) Weight N
(b) Work done J
Investigation: pulling a box across three surfaces
A class pulled the same box of sand 5 m across three surfaces. A force meter measured the steady pulling force each time.
| Surface | Pulling force (N) | Work done (J) |
|---|---|---|
| Polished floor | 12 | 60 |
| Carpet | 30 | |
| Grass | 42 |
Source: sample class results.
4. Complete Table 1 using W = F × d. The polished floor is done for you.
5. On which surface did the class transfer the most energy to the box and its surroundings? The box ends up still, so where did that energy go?
6. Two friends are helping a family move house. Kai holds a 20 kg box still at chest height for a whole minute while a door is unlocked. Lena slides an identical box 8 m along the hallway floor with a steady 50 N push. Kai says: “I did more work than Lena, because my arms are aching and hers aren’t.” Is Kai right? Explain, using calculations.
Work done by Lena J
Work done by Kai on his box J