Why objects need to reach escape velocity to escape from gravity?
2007-01-02 05:36:37 · 8 answers · asked by Dhiman B 2 in Science & Mathematics ➔ Astronomy & Space
If an object is travelling upward at a constant speed it is already escaping gravity because it is not slowing down! The only variable is how long it will take to get completely away from the Earth's gravity.
You will hear that 25,000 mph/40,000 kph is the earth's escape velocity from near the surface. What that means is that once you achieve that velocity you can turn off your engines and still manage to get away. Earth's escape velocity decrease with altitude, and at some point 100 mph, or even 1 mph, is all it takes.
PS to Corey M: The question as stated had the object traveling upwards at a constant velocity - *not* slowing down but overcoming gravity as it went, which means it had to keep applying power. If it travels at a constant velocity upwards it will keep going upwards until it needs no more power to get away from earth.
2007-01-02 06:03:47 · answer #1 · answered by hznfrst 6 · 1⤊ 0⤋
We do not escape Earth's gravity at any speed. No mater where a rocket went, straight up or otherwise , it would be under gravity from somewhere. The Earth is under gravity from the Sun and the Moon. The rockets used to go to the moon pass apoint where the moons gravity is stronger than the Earths. It was this sling shot effect that help the Apollo 13 astronauts on their return trip to Earth.
We go weightless in space as we reach escape velocity which is a misnomer (named wrong). It should be called free fall velocity as we are then falling at the same time as the earth is curving away from us.
2007-01-02 15:28:54 · answer #2 · answered by orion_1812@yahoo.com 6 · 0⤊ 0⤋
The initial velocity(u) of the car before speeding is 15 m/s because the car was moving at the constant velocity. The final velocity(v) after 15 s can be calculated as follows: Given: u = 15 m/s; f = 2.0 m/s^2, t = 15 s and let v be the final velocity(to be calculated) after 14 s v = u+ft = 15m/s + 2.0 m/s^2* 15 s = 15+30 = 45 m/s <= ans
2016-05-23 06:41:02 · answer #3 · answered by Jeanette 4 · 0⤊ 0⤋
i have a feeling that you are all wrong. no something travelling at 100 miles/hour will not escape earth's gravity, the space shuttle may be able to reach a top speed of 28000 mph, but only 17500 mph is required to escape earth's atmosphere and get into low earth orbit
2007-01-02 10:04:24 · answer #4 · answered by mcdonaldcj 6 · 0⤊ 1⤋
No any object traveling one hundred miles an hour verticaly would lose speed due to the pull of earth's gravity, as the speed gets slower, the increasing of the altitude slows down and eventually it would be zero miles/h and will turn over (unless it is a ball) and plumet to the the earth gaining speed again verticly losing altitude.
The guy above me said that the shuttle is 5,000,000 MPH? no it's top is 28,000 MPH as i read it in a book once.
2007-01-02 05:51:01 · answer #5 · answered by Crow 2 · 0⤊ 2⤋
In theory, it is possible to achieve escape velocity at any speed:
The escape speed depends on the mass and on your distance from the mass.
Ve = SQRT(2*G*M/d) where SQRT = square root, G is the constant of gravitation, M is the mass of the body you try to escape from, d is your distance from the centre of mass.
The escape velocity at the surface of Earth is 11.2 km/s (25,200 km/h).
The orbital speed of the lowest orbit is the escape speed divided by SQRT(2): 7.92 km/s (17,820 km/h).
The escape velocity at a distance of 637,800 km (100 times Earth's radius) is 1.12 km/s.
However, at the slow speed of 100 mi/h (0.044 km/s), you'd have to maintain this speed until you reach a distance of 250 million miles from Earth (the Sun is much closer than that!). You'd probably need so much fuel that it would prove impossible to build a space vehicle that large that could hold together under its own weight.
And by then, you'd have to contend with the Sun's gravity (at Earth's distance, the Sun's escape velocity is still a whopping 42.1 km/s (94,725 mi/h).
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In practice -- at least, using modern rockets -- if you cannot achieve low orbital speed (17,820 mi/h), by the time you leave the atmosphere, you won't escape.
2007-01-02 06:08:51 · answer #6 · answered by Raymond 7 · 0⤊ 2⤋
If you had some way of maintaining the 100 mph speed it would fly off into space!
2007-01-03 03:24:38 · answer #7 · answered by Billy Butthead 7 · 0⤊ 0⤋
they need to reach escape velocity to get away from the earths gravity force, that is how shuttles work, they go for more than 3 miles per second. u nedd to go over 5000000 miles per hour to escape earths gravity
2007-01-02 05:41:55 · answer #8 · answered by Harshil 2 · 0⤊ 3⤋