Secondary 2 Science Physical Sciences Quiz

Secondary 2 Science Quiz - Physical Sciences (Answer Key)

Section A: Energy and Work (Questions 1-5)

1. A student of mass 50 kg climbs from the ground floor to the 3rd floor of a school building. Each floor is 4 m high.

(a) State the principle of conservation of energy. [2] Answer: Energy cannot be created or destroyed [1], only converted from one form to another [1]. Alternative: The total amount of energy in a closed system remains constant [2].

(b) Calculate the gain in gravitational potential energy of the student. [2] Answer: Height climbed = 3 × 4 = 12 m [1] GPE = mgh = 50 × 10 × 12 = 6000 J [1]

2. Figure 1 shows a pendulum at different positions during its swing.

(a) At which position does the pendulum have maximum kinetic energy? [1] Answer: B [1]

(b) Explain your answer in part (a). [2] Answer: At position B, the pendulum is moving fastest [1] as all gravitational potential energy has been converted to kinetic energy [1].

3. A box is pushed across a rough floor with a constant force of 20 N for a distance of 5 m.

Calculate the work done on the box. [2] Answer: Work done = Force × Distance [1] Work done = 20 × 5 = 100 J [1]

4. State two forms of energy that a moving car possesses. [2] Answer:

1. Kinetic energy [1]
2. Gravitational potential energy (if above ground level) OR Chemical potential energy (in fuel) [1]

5. A ball is dropped from a height of 2 m. Just before it hits the ground, its kinetic energy is 10 J.

(a) What was the gravitational potential energy of the ball at 2 m height? [1] Answer: 10 J [1]

(b) Explain your answer using the principle of conservation of energy. [1] Answer: All gravitational potential energy is converted to kinetic energy during the fall [1].

Section B: Forces and Motion (Questions 6-10)

6. Figure 2 shows a girl pulling a trolley at constant speed.

(a) Draw and label the friction force acting on the trolley. [1] Answer: Arrow pointing opposite to direction of motion, labeled "friction" [1]

(b) State the size of the friction force if the pulling force is 15 N. [1] Answer: 15 N [1]

(c) Explain your answer in part (b). [1] Answer: At constant speed, forces are balanced/no resultant force [1].

7. A book rests on a table. The book has a weight of 8 N.

(a) What is the size of the normal force from the table on the book? [1] Answer: 8 N [1]

(b) State Newton's third law. [2] Answer: For every action, there is an equal and opposite reaction [2]. Alternative: When object A exerts a force on object B, object B exerts an equal and opposite force on object A [2].

8. List three effects that forces can have on objects. [3] Answer:

1. Change speed/accelerate [1]
2. Change direction [1]
3. Change shape/deform [1]

9. A car travels at a constant speed of 20 m/s for 10 seconds.

Calculate the distance travelled by the car. [2] Answer: Distance = speed × time [1] Distance = 20 × 10 = 200 m [1]

10. Explain why it is more difficult to stop a heavy truck than a light car when both are travelling at the same speed. [2] Answer: The truck has greater mass [1], so it has greater momentum/kinetic energy and requires more force to stop [1].

Section C: Light and Optics (Questions 11-15)

11. Figure 3 shows a light ray entering a glass block from air.

(a) Complete the ray diagram to show the path of light through and out of the glass block. [2] Answer: Ray bends toward normal on entry [1], travels straight through glass, bends away from normal on exit [1].

(b) Name the phenomenon that occurs when light enters the glass block. [1] Answer: Refraction [1]

12. A student uses a plane mirror to reflect sunlight.

(a) State the law of reflection. [2] Answer: The angle of incidence equals the angle of reflection [1], and the incident ray, reflected ray, and normal all lie in the same plane [1].

(b) If the angle of incidence is 30°, what is the angle of reflection? [1] Answer: 30° [1]

13. White light is passed through a triangular prism.

(a) What happens to the white light? [1] Answer: It splits into different colors/spectrum [1]

(b) Name this phenomenon. [1] Answer: Dispersion [1]

(c) Give one practical application of this phenomenon. [1] Answer: Rainbow formation/spectroscopy/prism in optical instruments [1]

14. Explain why a swimming pool appears shallower than it actually is. [2] Answer: Light from the bottom of the pool refracts when it leaves the water [1], making the bottom appear closer to the surface [1].

15. State two properties of the image formed by a plane mirror. [2] Answer:

1. Same size as object/virtual [1]
2. Laterally inverted/upright/same distance behind mirror [1]

Section D: Electricity (Questions 16-20)

16. A circuit contains a 6V battery connected to a 3Ω resistor.

(a) Calculate the current in the circuit. [2] Answer: I = V/R [1] I = 6/3 = 2 A [1]

(b) Calculate the power dissipated by the resistor. [2] Answer: P = VI or P = I²R [1] P = 6 × 2 = 12 W or P = 2² × 3 = 12 W [1]

17. Figure 4 shows two identical bulbs connected to a battery.

(a) Are the bulbs connected in series or parallel? [1] Answer: Parallel [1]

(b) If one bulb is removed, what happens to the brightness of the other bulb? [1] Answer: Stays the same/no change [1]

(c) Explain your answer in part (b). [1] Answer: Each bulb has its own complete circuit/same voltage across remaining bulb [1].

18. An electric kettle has a power rating of 2000 W and is used for 0.5 hours.

Calculate the energy consumed by the kettle. [2] Answer: E = P × t [1] E = 2000 × 0.5 = 1000 Wh or 3,600,000 J [1]

19. State two safety features found in household electrical systems and explain how each works. [4] Answer:

1. Feature: Fuse/Circuit breaker [1] How it works: Breaks the circuit when current exceeds safe limit/melts when overheated [1]

2. Feature: Earth wire/Residual current device [1] How it works: Provides alternative path for current/detects current leakage and cuts power [1]

20. A student connects three 1.5V cells in series.

(a) Calculate the total voltage provided by the cells. [1] Answer: 1.5 + 1.5 + 1.5 = 4.5 V [1]

(b) Draw a simple circuit diagram showing these cells connected to a bulb. [2] Answer: Three cells drawn in series (+ to -) [1] connected to a bulb symbol in a complete circuit [1]

Marking Notes:

• Accept alternative correct units (e.g., kJ for energy questions)
• Award method marks for correct formula even if calculation error
• Diagrams must show clear arrows and labels for full marks
• Accept scientifically accurate alternative wordings