Work and energy are measured in joules and work is calculated as force times distance, so this Year 9 sheet opens with the energy unit and the work formula. The answers record watt as the power unit and the conservation of energy.
Key Takeaways
The unit of work and energy is the joule (Q1).
Work is calculated as force × distance (Q2).
Q5 records the conservation of energy.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.What is the unit of work and energy?
(a) joule(b) newton(c) watt(d) pascal
2.Which formula is used to calculate the work done by a force?
(a) W = F × d(b) W = F ÷ d(c) W = m × a(d) W = P × t
3.What is the unit of power?
(a) watt(b) joule(c) newton(d) ampere
4.A stretched spring stores which type of energy?
(a) elastic potential energy(b) kinetic energy(c) chemical energy(d) nuclear energy
5.The law of conservation of energy states that energy can be transferred from one form to another but never created or destroyed. What is a correct statement of this law?
(a) Energy cannot be created or destroyed, only transferred(b) Energy is always lost when work is done(c) Energy is created during burning(d) Energy is destroyed when a machine is used
6.The kinetic energy of a moving object depends on its mass and its speed. What is the correct statement?
(a) Kinetic energy depends on mass and speed(b) Kinetic energy depends on height and mass(c) Kinetic energy depends on temperature(d) Kinetic energy depends on colour
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Define work done and state its unit.
8.Define power and state its unit.
9.State the law of conservation of energy.
10.Write the formula for gravitational potential energy and name each symbol.
11.Write the formula for kinetic energy and name each symbol.
12.What is efficiency and how is it calculated?
13.Give two energy transfers that take place in a moving car.
14.What happens to the wasted energy produced by a machine?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A force of 10 N moves an object through a distance of 5 m. Using W = F × d, calculate the work done.
16.3000 J of work is done in 10 s. Using P = W ÷ t, calculate the power.
17.A machine receives 1000 J of energy and transfers 750 J usefully. Calculate its efficiency as a percentage.
18.A 2 kg object is lifted through a height of 3 m. Using E = m × g × h with g = 10 N/kg, calculate its gain in gravitational potential energy.
19.A 4 kg object moves at a speed of 5 m/s. Using KE = ½ × m × v², calculate its kinetic energy.
20.An object gains 40 J of gravitational potential energy when it is raised through 2 m. Using E = m × g × h with g = 10 N/kg, find the mass of the object.
Answer Key
1. a) joule
2. a) W = F × d
3. a) watt
4. a) elastic potential energy
5. a) Energy cannot be created or destroyed, only transferred
6. a) Kinetic energy depends on mass and speed
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is the unit of work and energy?
The joule, option (a) in this worksheet (Q1).
Which formula calculates the work done by a force?
W = F × d, option (a) in this worksheet (Q2).
What does the conservation of energy state?
Energy cannot be created or destroyed, only transferred, option (a) in this worksheet (Q5).
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