MYTUTOR SUBJECT ANSWERS

449 views

What is escape velocity?

This is the minimum initial velocity required to move from a point to infinity in a gravitational field.

Infinity is defined to have a potential, V of zero; this is the point where the gravitational field has no influence on the object and no force is acting on it due to the gravitational field (in theory). In reality this point of infinity is simply described as a point incredibly far away as though the field is not acting on the object.

Note that the definition does not include the mass of the object and is only concerned with the grav. Field itself.

The formula used to calculate the escape velocity:           V_e = sqrt[2GM/r]

Where G is the Universal gravitational constant; M is the mass of the body producing the grav. Field; r is the radius of the body.

For example, on earth:

The Earth’s mass approximately: M = 6x10^24 kg;

Universal gravitational constant: G = 6.67×10^-11 m^3 kg^-1 s^-2;

Radius of Earth approximately: r = 6,400,000m.

    Sub in the numbers:

    V_e = sqrt[(2)(6x10^24)(6.67×10^-11)/(6,400,000)]

Results in:

The escape velocity of the earth: V_e = 11.2 km/s.

Any object, irrelevant of mass would require this initial velocity to escape the earth.

Space Rockets:

Of course rockets when sent to space, escaping earth’s field they are clearly not travelling anywhere near 11.2 km/s at launch. This is because the rocket is continuously accelerating as it pushes propellant out the exhaust and so travels upwards. Note the careful wording of the definition of escape velocity: “Initial velocity required” so this 11.2 km/s only applies to an object with no further acceleration.

Ashkan P. GCSE Physics tutor, A Level Physics tutor, GCSE Maths tutor...

2 years ago

Answered by Ashkan, an A Level Physics tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

57 SUBJECT SPECIALISTS

£20 /hr

Peter H.

Degree: Mathematics (Bachelors) - Durham University

Subjects offered: Physics, Maths+ 2 more

Physics
Maths
Further Mathematics
.STEP.

“About me: I am a Mathematics student at Durham University, and I am currently in my 3rd year. I would very much like to give assistance and help students of all abilities to reach the goals they aspire to in Maths and Physics, whether...”

MyTutor guarantee

£22 /hr

Cordelia W.

Degree: Mathematical Science (Masters) - Durham University

Subjects offered: Physics, Maths+ 1 more

Physics
Maths
Further Mathematics

“I LOVE maths and believe I can pass on my love of the subject. I have been teaching maths and physics for years. I taught myself maths and physics, I helped my friends understand both subjects, I went on toteach a whole secondary scho...”

£30 /hr

Hayden M.

Degree: Physics (Masters) - Warwick University

Subjects offered: Physics, Science+ 4 more

Physics
Science
Maths
Further Mathematics
English
Chemistry

“My name is Hayden. I am a 2nd year Physics student at The University of Warwick. I get excited aboutall things science and I hope that I can help you not only learn your material but alsounderstand why it is a useful thing to know.A...”

About the author

Ashkan P.

Currently unavailable: for new students

Degree: Medical Physics (Bachelors) - University College London University

Subjects offered: Physics, Maths

Physics
Maths

“Medical Physics student at UCL here to help you get up to speed with what our species understand about nature.”

MyTutor guarantee

You may also like...

Other A Level Physics questions

How can an object be accelerating if it does not change in speed?

An electron falling from one energy level to another emits a photon of wavelength 550nm. What is the difference between the two energy levels?

A car is moving along a straight horizontal road, with a constant acceleration. The car passes point A, with a speed of ums(-1). 10 seconds later, passes point B, with a speed of 45 ms(-1). The distance from A to B is 300m. Find u.

What is the 'centre of gravity' of an object and how do I calculate it?

View A Level Physics tutors

Cookies:

We use cookies to improve our service. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok