A projectile is thrown upward at an angle 60^ with the horizontal. The speed of the projectile is 20 ~m / s when its direction of motion is 45^ with the horizontal. The initial speed of the projectile is \_\_\_\_ m / s .

Correct answer: A. 20 2 Horizontal velocity is constant: v_x = u 60° = (u)/(2) . When direction is 45° with horizontal and speed is 20 m/s: v_x = 20 45° = 20 2 . (u)/(2) = 20 2 u = 40 2 = 20 2 m/s.

JEE Main 202622 JanuaryMorning Shift

Exam: JEE Main
Year: 2026
Date: 22 January
Shift: Morning Shift
Subject: Physics
Chapter: Motion in Two Dimensions

JEE Main 2026 · 22 January · Morning Shift · Physics · Motion in Two Dimensions

A projectile is thrown upward at an angle 60^ with the horizontal....

A projectile is thrown upward at an angle

60^{\circ}

with the horizontal. The speed of the projectile is

20 \mathrm{~m} / \mathrm{s}

when its direction of motion is

45^{\circ}

with the horizontal. The initial speed of the projectile is

\_\_\_\_

\mathrm{m} / \mathrm{s}

Options

A $20 \sqrt{2}$
B40
C $40 \sqrt{2}$
D $20 \sqrt{3}$

Correct answer

A. $20 \sqrt{2}$

Step-by-step solution

Horizontal velocity is constant:

v_x = u\cos 60° = \frac{u}{2}

.
When direction is

45°

with horizontal and speed is 20 m/s:

v_x = 20\cos 45° = \frac{20}{\sqrt{2}}

\frac{u}{2} = \frac{20}{\sqrt{2}} \Rightarrow u = \frac{40}{\sqrt{2}} = 20\sqrt{2}

m/s.

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