# physics

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1. A certain projectile is launched with an initial speed v0. At its highest point its speed is v0/6. What was the launch angle?

2. The "hang time" of a punt is measured to be 3.50 s. If the ball was kicked at an angle of 61.0° above the horizontal and was caught at the same level from which it was kicked, what was its initial speed? (Neglect air resistance.)

• physics -

1.The speed at the highest point is equal to v(x) since v(y) = 0 =>
v(x)=v₀/6.
v₀(x) =v(x) =v₀•cosα= v₀/6.
cosα=1/6=0.167,
α =arccos0.167=80.41°.
2.
t= 2vₒ•sinα/g
vₒ=g•t/2•sinα=9.8•3.5/2•sin61°=19.6 m/s

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