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_______ m/s A rocket is fired straight up through the atmosphere from the South

ID: 1323299 • Letter: #

Question

_______ m/s

A rocket is fired straight up through the atmosphere from the South Pole, burning out at an altitude of 247 km when traveling at 4.90 km/s. What maximum distance from the launch site does it travel before falling back to Earth?

____ m

1. A space probe is fired as a projectile from the Earth's surface with an initial speed of 1.58 x 10^4 m/s. What will its speed be when it is very far from the Earth? Ignore atmospheric friction and the rotation of the Earth. _______ m/s A rocket is fired straight up through the atmosphere from the South Pole, burning out at an altitude of 247 km when traveling at 4.90 km/s. What maximum distance from the launch site does it travel before falling back to Earth? ____ m

Explanation / Answer

Initial speed of the space probe is, v0 = 1.58 * 104 m/s

Mass of the Earth is, M = 5.972 * 1024 kg

Radius of the earth is R = 6.371 * 106 m

Universal gravitational constant is, G = 6.67384 * 10-11 m3/kg.s2

Initial energy of the space probe is,

Ei = (1/2) m v02 - G m M / R

where m is the mass of the space probe.

Final energy of the space probe is,

Ef = (1/2) m v2 - G m M / r

where r >> R and we take it to be infinite.

From the law of conservation of energy,

Ef = Ei

(1/2) m v2 - G m M / r = (1/2) m v02 - G m M / R

v2 = 2 G M / r + v02 - 2 G M / R

v2 = 0 + 1.58 * 104 * 1.58 * 104 - 6.67384 * 10-11 * 5.972 * 1024 / 6.371 * 106

v2 = 1.870812612 * 108 m2/s2

v = 1.367776521 * 104 m/s = 13677.765 m/s is the speed of the space probe when it is very far away from the Earth.

A rocket is fired straight up through the atmosphere from the South Pole, burning out at an altitude of 247 km when traveling at 4.90 km/s.

Initial speed of the space probe is, v0 = 4.9 * 103 m/s

Mass of the Earth is, M = 5.972 * 1024 kg

Radius of the earth is R = 6.371 * 106 m

Universal gravitational constant is, G = 6.67384 * 10-11 m3/kg.s2

Since the rocket is at a distance of 247 km from the Earth's surface, g will have a slightly different value than the one we use for objects on/near the surface of the earth.

g = GM / r2

Here, r = R (Earth radius) + the altitude height

r = 6.371 * 106 + 0.247 * 106

r = 6.618 * 106 m

Thus,

g = 6.67384 * 10-11 * 5.972 * 1024 / (6.618 * 106 * 6.618 * 106)

g = 9.1 m/s2

Maximum height (maximum distance from the launch site) of this rocket can reach is,

H = v02 / 2g

H = 4.9 * 103 * 4.9 * 103 / (2 * 9.1)

H = 1.319230769 * 106 m = 1319230.769 m