A distress flare is fired from the edge of a -high cliff so that it lands on the…

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A distress flare is fired from the edge of a

50\,\text{m}

-high cliff so that it lands on the surface of the sea at a point

80\,\text{m}

horizontally from the base of the cliff. The flare is launched

30^{\circ}

above the horizontal. Neglect air resistance and take

g=9.8\,\text{m}\!\cdot\!\text{s}^{-2}

. What is the required initial speed of the flare? (a)

29\,\text{m}\!\cdot\!\text{s}^{-1}

(b)

18\,\text{m}\!\cdot\!\text{s}^{-1}

(c)

21\,\text{m}\!\cdot\!\text{s}^{-1}

(d)

31\,\text{m}\!\cdot\!\text{s}^{-1}