A particle is projected from ground at angle 45° with initial velocity 20√2 m/s. Find the change in velocity during its whole journey.
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Question

A particle is projected from ground at angle 45° with initial velocity 20√2 m/s. Find the change in velocity during its whole journey.

G1 Physics · Accepted Answer

Initial velocity is v⃗(initial) = 20î + 20ĵ m/s. At the same level on return, the horizontal component is unchanged and the vertical component reverses, so v⃗(final) = 20î - 20ĵ m/s. Hence Δv⃗ = v⃗(final) - v⃗(initial) = -40ĵ m/s. Therefore option A is correct.