A paratrooper jumps from an aeroplane and opens a parachute after 2 s of free fall and starts deaccelerating with 3 m/s². At 10 m height from ground, while descending with the help of parachute, the speed of paratrooper is 5 m/s. The initial height of the aeroplane i $s _____m.$
(g = 10 m/s²)

Question

A paratrooper jumps from an aeroplane and opens a parachute after 2 s of free fall and starts deaccelerating with 3 m/s². At 10 m height from ground, while descending with the help of parachute, the speed of paratrooper is 5 m/s. The initial height of the aeroplane i $s _____m.$

(g = 10 m/s²)

G1 Physics · Accepted Answer

During the first 2 s, the paratrooper is in free fall. Distance fallen: x₁ = ½gt² = ½×10×2² = 20 m. Speed after 2 s: v₁ = gt = 10×2 = 20 m/s. After the parachute opens, the paratrooper decelerates at 3 m/s². At point C, 10 m above the ground, the speed is v₂ = 5 m/s. Use v₂² = v₁² + 2as, with a = -3 m/s². Therefore, 5² = 20² - 2×3×x₂. Hence, 25 = 400 - 6x₂, so x₂ = 375/6 = 62.5 m. The final 10 m from C to the ground gives x₃ = 10 m. Therefore the initial height is H = x₁+x₂+x₃ = 20+62.5+10 = 92…

A paratrooper jumps from an aeroplane and opens a parachute after 2 s of free fall and starts deaccelerating with 3 m/s². At 10 m height from ground, while descending with the help of parachute, the speed of paratrooper is 5 m/s. The initial height of the aeroplane i s _____m. (g = 10 m/s²)