Haryana Board (HBSE) Class 11 Physics Half Yearly Question Paper 2026 Answer Key
Instructions :
• All questions are compulsory.
• Questions (1-9) carry 1 mark each.
• Questions (10-12) carry 2 marks each.
• Questions (13-14) carry 3 marks each.
• Question (15) case study, carry 4 marks.
• Questions (16-17) carry 5 marks each.
1. SI Unit of Impulse is :
(A) N-m
(B) N-s
(C) Kg m s–2
(D) N-s–1
Answer – (B) N-s
2. Potential energy cannot be expressed in :
(A) J
(B) N-m
(C) N-s
(D) N-s–1
Answer – (C) N-s
3. The centre of mass of system of particles does not depend on :
(A) Mass of particles
(B) Force on particles
(C) Position of particles
(D) Relative distance between particles
Answer – (B) Force on particles
4. A body of mass 2 kg has acceleration of 20 ms–2, the force on the body is :
(A) 10 N
(B) 40 N
(C) 20 N
(D) 80 N
Answer – (B) 40 N
Force = mass × acceleration = 2 kg × 20 ms–2 = 40 N
5. Assertion (A) : The speed of an object can never be negative.
Reason (R) : Speed is a scalar quantity.
(A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(C) Assertion is true but Reason is false.
(D) Assertion is false but Reason is also false.
Answer – (A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
6. Assertion (A) : In elastic collision, kinetic energy is conserved.
Reason (R) : Total energy is always conserved.
(A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(C) Assertion is true but Reason is false.
(D) Assertion is false but Reason is true.
Answer – (B) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
7. The dimension formula of pressure is ………….
Answer – [M L–1 T–2]
8. The dot product of two mutual perpendicular vectors is ………..
Answer – Zero
9. Which physical quantity is represented by the area under the velocity time curve?
Answer – Displacement
10. Write the significant figures of the following :
(i) 46.7
Answer – 3 significant figures
(ii) 10.04
Answer – 4 significant figures
11. Define Torque. Write its relation with angular acceleration.
Answer – It is the tendency of a force to turn, twist, or rotate an object around a pivot point or axis of rotation. SI unit is N-m.
Formula, τ = Iα
τ = Net torque applied to the object
I = Moment of inertia (the rotational analogue of mass, measuring resistance to changes in rotation)
α = Angular acceleration (the rate of change of angular velocity)
12. What value of constant a if vector A = 2i + aj + k is perpendicular to vector B = 4i – 3j + k.
Answer – Here, A = 2i + aj + k
B = 4i − 3j + k
Since A ⟂ B,
Two vectors are perpendicular if and only if their dot product equals to zero.
A . B = 0
(2)(4) + (A)(−3) + (1)(1) = 0
8 − 3a + 1 = 0
– 3a = – 9
a = 3
13. Derive equations s = ut + ½at2, where symbols have their usual meaning.
Answer – Average velocity (vavg) = (u + v) / 2
Substituting v = u + at into the average velocity equation,
vavg = (u + u + at) / 2 = u + ½at
Displacement (s) is the product of average velocity and time, s = vavg × t
Therefore, s = (u + ½at) × t = ut + ½at2
14. What is uniform circular Motion? Define Angular Momentum. Write its unit.
Answer – The motion of a body along a circular path with constant speed is called uniform circular motion.
The moment of linear momentum of a particle about a point or axis is called angular momentum.
SI Unit is kg m2 s–1 (or J-s)
15. CASE STUDY : A wooden block A of mass 6 kg is placed on another identical block B of mass 8 kg lying on a horizontal wooden table. It is found that when a force of 12 N is applied on block A, it just begins to slide over the surface of block B. The coefficient of friction (µ) between the surface of block B and the table is 0.25. Given, g = 10 ms–2
Questions :
(i) The value of coefficient of friction for ideal smooth surface is :
(A) 1
(B) Infinity
(C) 1.5
(D) 0
Answer – (D) 0
(ii) The coefficient of friction (µ) between surface of two block A and B is :
(A) 0.10
(B) 0.15
(C) 0.20
(D) 0.25
Answer – (C) 0.20
(iii) The normal reaction on block A due to block B is :
(A) 40 N
(B) 50 N
(C) 60 N
(D) 80 N
Answer – (C) 60 N
NA = mAg = 6 × 10 = 60 N
16. Write various rules for calculating significant figures. 5.74 g of a substance occupies 1.2 cm3. Express its density by keeping the significant figures in view.
Answer – Rules for calculating significant figures :
(i) All non-zero digits are significant.
(ii) Zeros between two non-zero digits are significant.
(iii) Leading zeros are not significant.
Trailing zeros in a decimal number are significant.
(iv) In multiplication or division, the result should have the same number of significant figures as the quantity having the least significant figures.
density (ρ) = mass / volume
ρ = 5.74 / 1.2 = 4.78333…. g/cm3
Since this is a division operation, the final answer must match the least number of significant figures in the given data. The volume (1.2 cm3) has only two significant figures, so we round our final answer to two significant figures.
Thus, the density of the substance is 4.8 g/cm3
17. A projectile is thrown at an angle θ from the horizontal with velocity u under the gravitational field of Earth. Define and find expression for Time of flight, Horizontal Range and Maximum Height.
Answer : Time of Flight – The time of flight is the total time taken by the projectile to complete its motion through the air, that is, the time interval between its projection and the moment it returns to the same vertical level from which it was projected.
T = 2usinθ / g
• Horizontal Range – The horizontal range of a projectile is the total horizontal distance covered by it between the point of projection and the point where it again reaches the same vertical level.
R = u2sin2θ / g
• Maximum Height – The maximum height is the greatest vertical distance attained by the projectile above the horizontal plane during its motion.
Hmax = u2sin2θ / 2g