Question

A helicopter is hovering in the air, just above some firefighters who have been surrounded by a fire. A box containing food and additional personal protective equipment for the firefighters is dropped from the helicopter. The helicopter operator uses his instruments to calculate a height of 70 m above the ground. Calculate: If a kind of parachute is placed on the box that reduces the acceleration of the fall by a quarter, calculate again the time it takes the box to fall and the speed with which it hits the ground.

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Answer to a math question A helicopter is hovering in the air, just above some firefighters who have been surrounded by a fire. A box containing food and additional personal protective equipment for the firefighters is dropped from the helicopter. The helicopter operator uses his instruments to calculate a height of 70 m above the ground. Calculate: If a kind of parachute is placed on the box that reduces the acceleration of the fall by a quarter, calculate again the time it takes the box to fall and the speed with which it hits the ground.

Expert avatar
Brice
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113 Answers
1. La aceleración reducida es:

a' = \frac{g}{4} = \frac{9.8}{4} \, \text{m/s}^2 = 2.45 \, \text{m/s}^2 ,

donde g = 9.8 \, \text{m/s}^2 .

2. Usar la fórmula de caída libre con aceleración reducida para encontrar el tiempo de caída:

h = \frac{1}{2} a' t^2 ,

donde h = 70 \, \text{m} .

3. Sustituir los valores:

70 = \frac{1}{2} \times 2.45 \times t^2 .

4. Resolver para t :

t^2 = \frac{70 \times 2}{2.45} ,

t^2\approx57.14 ,

t\approx7.56\text{s} .

5. Calcular la velocidad con la que impacta el suelo usando:

v = a' \times t .

6. Sustituir los valores:

v=2.45\times7.56 ,

v\approx18.52\,\text{m/s} .

Por lo tanto, el tiempo en que cae la caja es aproximadamente 7.56\,\text{s} y la velocidad con la que impacta el suelo es aproximadamente 18.52\,\text{m/s} .

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