Q50. Consider a ball thrown vertically upward:
(1) its upward velocity decreases at rate g;
(2) gravity remains downward.
[RRB Group D — 08 Jan 2026, Shift 3]
(A) Both statements are false
(B) Only statement 2 is true
(C) Only statement 1 is true
(D) Both statements are true
Answer: (D) Both statements are true
Explanation: While rising, the ball has upward velocity but downward gravitational acceleration. Therefore the upward velocity steadily decreases by about g each second. At its highest point velocity is momentarily zero, yet acceleration still acts downward.
Q49. Which statement about potential energy is correct?
[RRB Group D — 14 Dec 2025, Shift 1]
(A) It is always zero on the ground
(B) Its value can be negative relative to a chosen reference
(C) It never converts into kinetic energy
(D) It depends solely on mass
Answer: (B) Its value can be negative relative to a chosen reference
Explanation: Gravitational potential energy near the surface can be written mgh, with h measured from an arbitrarily chosen zero level. A position below that level has negative h and negative relative potential energy. Energy differences, rather than its chosen zero, determine motion.
Q48. When gravitational potential energy becomes kinetic energy in free fall, what happens to total energy?
[RRB Group D — 10 Dec 2025, Shift 1]
(A) Total energy remains constant
(B) Energy disappears from the system
(C) Total mechanical energy must increase
(D) New energy is continuously created
Answer: (A) Total energy remains constant
Explanation: For ideal free fall without air resistance, gravitational potential energy decreases while kinetic energy increases by exactly the same amount. Their sum, mechanical energy, remains constant; this illustrates conservation of energy rather than energy creation or destruction.
Q47. For an object dropped straight down and falling freely, what happens to its direction of motion?
[RRB Group D — 08 Dec 2025, Shift 3]
(A) It becomes horizontal
(B) It turns continuously
(C) It points opposite to gravity
(D) It remains downward
Answer: (D) It remains downward
Explanation: An object dropped vertically from rest, with no horizontal velocity and no air force, accelerates toward Earth’s centre. Its speed increases, but its downward direction does not change. This assumes the local gravitational field is approximately vertical.
Q46. For an object projected vertically upward, which direction does gravitational acceleration take while it rises?
[RRB Group D — 08 Dec 2025, Shift 2]
(A) Along the upward motion
(B) Zero at the peak
(C) Opposite the upward motion
(D) Always increasing upward
Answer: (C) Opposite the upward motion
Explanation: Gravity points toward Earth’s centre, so during ascent it acts opposite to the body’s upward velocity. That downward acceleration reduces the upward speed until the highest point. Even at the top, acceleration remains downward rather than vanishing.
Q45. As a body falls freely from height, into which form is its gravitational potential energy converted?
[RRB Group D — 04 Dec 2025, Shift 1]
(A) Sound energy
(B) Thermal energy
(C) Chemical energy
(D) Kinetic energy
Answer: (D) Kinetic energy
Explanation: As the descending body loses altitude, its gravitational potential energy mgh decreases. In ideal free fall, this energy appears as increased kinetic energy ½mv². Mechanical energy is conserved provided air drag and other dissipative effects are neglected.
Q44. A body is dropped from rest for 3 s with g = 10 m/s². What downward velocity does it attain?
[RRB Group D — 27 Nov 2025, Shift 1]
(A) 20 m/s
(B) 30 m/s
(C) 10 m/s
(D) 40 m/s
Answer: (B) 30 m/s
Explanation: For constant acceleration, final velocity is v = u + gt. Since the object is released from rest, u = 0. Substituting g = 10 m/s² and t = 3 s gives v = 30 m/s downward.
Q43. As an object falls freely, how do its potential energy and kinetic energy change?
[SSC CHSL Tier-I — 22 Nov 2025, Shift 3]
(A) Both decrease
(B) Both increase
(C) Potential decreases, kinetic increases
(D) Potential increases, kinetic decreases
Answer: (C) Potential decreases, kinetic increases
Explanation: Height decreases throughout descent, reducing gravitational potential energy mgh. Meanwhile, gravity accelerates the object and increases its speed, raising ½mv². If no dissipative force acts, the lost potential energy exactly equals the gained kinetic energy.
Q42. Judge two statements: I. Weight has magnitude only. II. Weight acts vertically downward.
[SSC CHSL Tier-I — 14 Nov 2025, Shift 1]
(A) Only I is correct
(B) Only II is correct
(C) Both are correct
(D) Neither is correct
Answer: (B) Only II is correct
Explanation: Weight is the gravitational force on a body, W = mg. A force has both magnitude and direction, so statement I is wrong. Near Earth’s surface the direction is toward Earth’s centre, approximately vertically downward, validating statement II.
Q41. A ball goes vertically upward at 10 m/s. With g = 9.8 m/s², what maximum height does it reach?
[SSC CGL — 25 Sep 2025, Shift 2]
(A) 1.02 m
(B) 5.10 m
(C) 10.2 m
(D) 20.4 m
Answer: (B) 5.10 m
Explanation: At the top the ball’s instantaneous velocity is zero. Using v² = u² − 2gh gives h = u²/(2g) = 100/19.6, approximately 5.10 m. This neglects air resistance and measures height above the launch point.
