Grade 12 Physics practice questions – Lebanese curriculum

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They are a sample from EduRise's Grade 12 Physics question bank (1,560 questions across 15 chapters), written to follow the Lebanese curriculum. Each chapter on EduRise has its own practice set and a timed exam.

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Question 1

A minibus on the Beirut corniche of total mass 2 500 kg moves at 36 km/h. What is its kinetic energy?

Accepted Answer

1.25 × 10⁵ J. v = 36/3.6 = 10.0 m/s; KE = ½ m v² = ½ × 2500 × 10.0² = 1.25 × 10⁵ J.

Question 2

A spring of stiffness k = 80 N/m is stretched by 8.0 cm. What elastic potential energy does it store?

Accepted Answer

0.256 J. PEe = ½ k x² with x = 8.0 cm = 0.08 m: PEe = ½ × 80 × 0.08² = 0.256 J.

Question 3

When two bodies stick together after a collision, the kinetic energy of the system:

Accepted Answer

decreases. Perfectly inelastic collision: part of KE becomes heat and deformation.

Question 4

A car of mass 1 500 kg moves at 18 km/h. What is the magnitude of its linear momentum?

Accepted Answer

7 500 kg·m/s. v = 18/3.6 = 5.00 m/s; p = m v = 1500 × 5.00 = 7 500 kg·m/s.

Question 5

A disc of diameter 20 cm turns at 15 rad/s about its axis. What is the speed of a point on its rim?

Accepted Answer

1.50 m/s. R = 20/2 = 10 cm = 0.1 m; v = R ω = 0.1 × 15 = 1.50 m/s.

Question 6

A disc of diameter 40 cm turns at 8.0 rad/s about its axis. What is the speed of a point on its rim?

Accepted Answer

1.60 m/s. R = 40/2 = 20 cm = 0.2 m; v = R ω = 0.2 × 8 = 1.60 m/s.

Question 7

The abscissa of an oscillator is x = 0.05 cos(20t − π/2) (SI). What is its proper period?

Accepted Answer

0.314 s. ω₀ = 20 rad/s; T₀ = 2π/ω₀ = 2π/20 = 0.314 s. The amplitude is 5.0 cm.

Question 8

The abscissa of an oscillator is x = 0.02 cos(40t) (SI). What is its proper period?

Accepted Answer

0.157 s. ω₀ = 40 rad/s; T₀ = 2π/ω₀ = 2π/40 = 0.157 s. The amplitude is 2.0 cm.

Question 9

A spring–mass oscillator of proper frequency 1.6 Hz is driven by a motor with an eccentric turning at 150 rpm. In steady state, at what frequency does the oscillator vibrate?

Accepted Answer

2.50 Hz. Forced oscillations take the exciter frequency: fₑ = N/60 = 150/60 = 2.50 Hz.

Question 10

In forced oscillations, the device that imposes its frequency is called:

Accepted Answer

the exciter. The exciter drives; the resonator responds.

Question 11

A conducting rod of length ℓ = 50 cm slides at constant speed v = 5.0 m/s on two horizontal rails in a uniform vertical magnetic field B = 0.40 T. What is the magnitude of the induced emf?

Accepted Answer

1.00 V. e = Bℓv = 0.40 × 0.50 × 5.0 = 1.00 V (ℓ in metres).

Question 12

A coil turns at 1 500 turns per minute in a uniform magnetic field. What is the frequency of the induced emf?

Accepted Answer

25.0 Hz. f = number of turns per second = 1 500/60 = 25.0 Hz (period T = 1/f = 40.0 ms).

Question 13

A coil stores 4.0 mJ when it carries a current I. What energy does it store when the current becomes I/2?

Accepted Answer

1.00 mJ. W = ½ L i² is proportional to i²: W' = 4.0 × (1/2)² = 1.00 mJ.

Question 14

When the current through a coil increases, the self-induced emf:

Accepted Answer

is negative and opposes the growth. di/dt > 0 → e = −L di/dt < 0 (Lenz).

Question 15

What is the time constant of an RC circuit with R = 2.0 kΩ and C = 100 μF?

Accepted Answer

200 ms. τ = RC = 2.0 × 10³ × 100 × 10⁻⁶ = 0.200 s = 200 ms.

Grade 12 Physics Questions and Answers

15 Grade 12 Physics practice questions

1. A minibus on the Beirut corniche of total mass 2 500 kg moves at 36 km/h. What is its kinetic energy?

2. A spring of stiffness k = 80 N/m is stretched by 8.0 cm. What elastic potential energy does it store?

3. When two bodies stick together after a collision, the kinetic energy of the system:

4. A car of mass 1 500 kg moves at 18 km/h. What is the magnitude of its linear momentum?

5. A disc of diameter 20 cm turns at 15 rad/s about its axis. What is the speed of a point on its rim?

6. A disc of diameter 40 cm turns at 8.0 rad/s about its axis. What is the speed of a point on its rim?

7. The abscissa of an oscillator is x = 0.05 cos(20t − π/2) (SI). What is its proper period?

8. The abscissa of an oscillator is x = 0.02 cos(40t) (SI). What is its proper period?

9. A spring–mass oscillator of proper frequency 1.6 Hz is driven by a motor with an eccentric turning at 150 rpm. In steady state, at what frequency does the oscillator vibrate?

10. In forced oscillations, the device that imposes its frequency is called:

11. A conducting rod of length ℓ = 50 cm slides at constant speed v = 5.0 m/s on two horizontal rails in a uniform vertical magnetic field B = 0.40 T. What is the magnitude of the induced emf?

12. A coil turns at 1 500 turns per minute in a uniform magnetic field. What is the frequency of the induced emf?

13. A coil stores 4.0 mJ when it carries a current I. What energy does it store when the current becomes I/2?

14. When the current through a coil increases, the self-induced emf:

15. What is the time constant of an RC circuit with R = 2.0 kΩ and C = 100 μF?

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