Position of an ant (S in metres) moving in Y-Z plane is given by $\vec{S}$ = 2t²ĵ + 5k̂ (where t is in second). The magnitude and direction of velocity of the ant at t = 1 s will be :
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Question

Position of an ant (S in metres) moving in Y-Z plane is given by S ⃗ \vec{S} S = 2t²ĵ + 5k̂ (where t is in second). The magnitude and direction of velocity of the ant at t = 1 s will be :

G1 Physics · Accepted Answer

v⃗ = dS⃗/dt = 4t ĵ At t = 1 s, v⃗ = 4ĵ m/s Therefore, speed = 4 m/s and the direction is along +y. Correct option: D.