Q1. A 10 kg object is lifted to a height of 5 m. What is the work done against gravity? (Take g = 10 m/s²)
Solution:
Work done W = mgh = 10 kg × 10 m/s² × 5 m = 500 J.
⏱ Time: 0s
Q2. A person walks 3 km at a speed of 4 km/h and then runs 2 km at a speed of 8 km/h. What is the total time taken? (2020)
Solution:
Time walking = 3 km / 4 km/h = 0.75 hours; Time running = 2 km / 8 km/h = 0.25 hours. Total time = 0.75 + 0.25 = 1 hour.
⏱ Time: 0s
Q3. What is the total capacitance of two capacitors, C1 = 3μF and C2 = 6μF, connected in series? (2022)
Solution:
The formula for total capacitance in series is 1/C_eq = 1/C1 + 1/C2. Thus, 1/C_eq = 1/3 + 1/6 = 1/2, so C_eq = 2μF.
⏱ Time: 0s
Q4. Which of the following materials has the highest speed of sound?
Solution:
Sound travels fastest in solids; hence, the speed of sound in steel is higher than in air, water, or wood.
⏱ Time: 0s
Q5. A 5 kg object is lifted to a height of 10 m. What is the potential energy gained by the object? (Take g = 10 m/s²)
Solution:
Potential energy PE = mgh = 5 kg * 10 m/s² * 10 m = 500 J.
⏱ Time: 0s
Q6. A 1 kg block of metal at 100°C is placed in 2 kg of water at 20°C. If the final temperature is 30°C, what is the specific heat capacity of the metal? (2023)
Solution:
Using conservation of energy: m1c1(T1 - Tf) = m2c2(Tf - T2), we find c1 = 2 J/kg°C.
⏱ Time: 0s
Q7. A capacitor stores energy in the form of which type of field?
Solution:
A capacitor stores energy in the form of an electric field between its plates.
⏱ Time: 0s
Q8. What is the magnification produced by a concave lens if the object is placed at a distance of 30 cm and the focal length of the lens is 15 cm? (2022)
Solution:
Using the lens formula and magnification formula, we find the magnification m = -v/u = -1.
⏱ Time: 0s
Q9. What is the total capacitance of two capacitors of 3 µF and 6 µF in parallel?
Solution:
In parallel, the total capacitance is the sum: C_total = C1 + C2 = 3 µF + 6 µF = 9 µF.
⏱ Time: 0s
Q10. A 5 kg block of metal is heated from 20°C to 100°C. If the specific heat capacity of the metal is 0.5 J/g°C, how much heat is required? (2023)
Solution:
Heat (Q) = m * c * ΔT = 5000 g * 0.5 J/g°C * (100°C - 20°C) = 5000 * 0.5 * 80 = 200000 J = 2000 J.
