Escape Velocity Interactive (163.0K)
Your mission: to determine how fast to fire a rocket so that it escapes the gravity of its planet. Your tool: the displayed escape velocity calculation (based on Newtonian physics). Your options: choose one of four planets in our Solar System, or make up a new one with radius and mass you choose. Then set an initial velocity and FIRE! Does it matter whether you point the rocket up horizontal or vertical? What will the rocket’s path look like at different velocities? Find out with this Interactive.

1		What simple math ratio allows us to compare the escape and orbital velocities? Need a Hint?
			A)	Escape velocity is about 1.4X greater than orbital velocity.
			B)	Escape velocity must be twice as fast as orbital velocity.
			C)	Escape velocity is four times faster than orbital velocity.
			D)	The two velocities are unrelated.

While many probes, such as the Voyages, have left the Earth behind, only one program has allowed men to achieve this speed.

2		Which astronauts have travelled at more than 25,000 mph? Need a Hint?
			A)	Everyone who has been in Earth orbit.
			B)	The 27 Apollo astronauts who went around the Moon.
			C)	The 12 astronauts who walked on the Moon.
			D)	No human can stand this speed.

We can talk about the escape velocities of objects leaving stars as well as planets. Let's study the speed that particles must be moving to escape our Sun.

3		Solar wind particles must be moving how fast to leave our star, given that our Sun is 333,000 times more massive than Earth, and 110 times larger in radius? Need a Hint?
			A)	6000 times our own escape velocity
			B)	78 times our escape velocity.
			C)	55 times our escape velocity.
			D)	32 times our escape velocity.

This has practical application to the Voyager missions, encounters betwen Earth and passing asteroids and comets, and even to the compositons of atmopsheres of bodies.

4		Io volcanoes are seen to spew ash so high that some of it is escaping that moon of Jupiter essentially the same size and mass as our own moon. Given our Moon's surface gravity is 1/6 g, how fast must this debris be ejected from Io's vents? Need a Hint?
			A)	About 3,000 mph.
			B)	About 4,200 mph.
			C)	About 5,600 mph.
			D)	about 25,000 mph.

When Einstein noted that nothing can exceed the speed of light, 300,000 km/sec, Schwartzschild noted that this also meant that a Black Hole would have around it a radius where light would have to be travelling faster than this to escape, which was impossible.

5		Given that the mass of our Sun is about 2 E 30 kg, and that the minimum mass for collapse to a black hole is 3 solar masses, use the value of c = 300,000,000 meters/second and the value of G = 6.67 E-11 to calculate the Schwartzschild radius of this smallest of black holes in kilometers. Need a Hint?
			A)	About nine meters.
			B)	About nine kilometers.
			C)	About 900 kilometers.
			D)	About an A.U.