A projectile is fired at 53° with speed u. When its velocity makes an angle 37° above the horizontal, its speed is:
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A projectile is fired at 53° with speed u. When its velocity makes an angle 37° above the horizontal, its speed is:

G1 Physics · Accepted Answer

At that instant, vₓ = 3u/5. Since the velocity makes 37° above horizontal, vᵧ = vₓ tan37° = (3u/5)(3/4) = 9u/20. Therefore v = √[(3u/5)²+(9u/20)²] = u√[(144+81)/400] = 15u/20 = 3u/4.