JEE Main · 2026 · 22 Jan 2026 · Shift 1 · Kinematics

A projectile is thrown upward at an angle

6 0^{\circ}

with the horizontal. The speed of the projectile is 20 m/s when its direction of motion is

4 5^{\circ}

with the horizontal. The initial speed of the projectile is ______ m/s.

(A) $402$
(B)40
(C) $203$
(D) $202$ ✓ Correct

Answer: (D)

Solution

The horizontal component of velocity is unchanged throughout the flight. When the velocity makes

4 5^{\circ}

and equals

20 m/s

, its horizontal part is

20 cos 4 5^{\circ} = \frac{20}{2}

. At launch the horizontal part is

u cos 6 0^{\circ}

. Equating the two,

u cos 6 0^{\circ} = \frac{20}{2}

, so

u = \frac{20/ 2}{1/2} = \frac{40}{2} = 202 m/s .

JEE Main · 2026 · 22 Jan 2026 · Shift 1 · Single correct option

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