A projectile is given an initial velocity of $$5$$ $$m/s$$ at an angle $$30$$° below horizontal from the top of a building $$25$$ m high. Find (a) the time after which it hits the ground; (b) the distance from the building where it strikes the ground. (g$$ $$=$$ $$10$$ $$m/s2)

Question

Infinity Learn · Accepted Answer

The projectile is thrown from point O and lands at point A on the ground. From O to A : $$sy=$$−$$25$$ m,  $$uy=$$−$$5$$ $$sin$$ $$30$$°$$=$$−$$2.5$$ $$m/s$$ (negative$$ because vertical component acts $$downwards)(a) We have $$ay=$$−$$g=$$−$$10$$  $$m/s2$$     $$sy=uyt+1/2ayt2$$ −$$25=$$−$$2.5t$$−$$1/210t2So$$, therefore $$10t2$$ $$+$$ $$5t$$ $$-$$ $$50$$ $$=$$ $$0$$. On solving, we get is t $$=$$ $$2s$$, $$-2.5$$ s.The relevant time is $$2s$$.(b) $$sx=uxt=5cos30$$°$$2=53$$ m.

A projectile is given an initial velocity of 5 m/s at an angle 30° below horizontal from the top of a building 25 m high. Find (a) the time after which it hits the ground; (b) the distance from the building where it strikes the ground. (g = 10 m/s²)

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A projectile is given an initial velocity of 5 m/s at an angle 30° below horizontal from the top of a building 25 m high. Find (a) the time after which it hits the ground; (b) the distance from the building where it strikes the ground. (g = 10 m/s2)

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A projectile is given an initial velocity of 5 m/s at an angle 30° below horizontal from the top of a building 25 m high. Find (a) the time after which it hits the ground; (b) the distance from the building where it strikes the ground. (g = 10 m/s²)