# physics

posted by .

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after it had passed the Earth. Suppose that at its closest approach, the asteroid was 84600 miles from the center of the Earth -- about a third of the distance to the Moon.

(a) Find the speed of the asteroid at closest approach, assuming its speed at infinite distance to be zero and considering only its interaction with the Earth.

(b) Observations indicate the asteroid to have a diameter of about 2.0 km. Estimate the kinetic energy of the asteroid at closest approach, assuming it has an average density of 3.33 g/cm3. (For comparison, a 1-megaton nuclear weapon releases about 5.6 1015 J of energy.)

• physics -

F = G m Me/r^2
potential energy relative to zero at infinity = -G m Me/r
here r = 84600 miles
convert that to meters
then
potential energy lost = Kinetic energy gained
G m Me/r = (1/2)m v^2
so
v^2 = 2 G Me/r

for part b you need m
diameter = 2*10^3
so
diameter/2 = radius = 1,000 meters
convert density to kg/m^3
3.33 g/cm^3 * (1kg/10^3g) * (10^6 cm^3/m^3) = 3330 kg/m^3
m = density * (4/3)pi (diameter/2)^3

then do Ke = (1/2) m v^2

• physics - reply is here for asteroid -

This is where I posted the reply to the multiple postings.

## Similar Questions

1. ### physics

Consider an asteroid with a radius of 15.5 km and a mass of 3.46E+15 kg. Assume the asteroid is roughly spherical. What is the acceleration due to gravity on the surface of the asteroid?
2. ### physics

Evidence suggests that there are trillions of dollars' worth of minerals and metals buried in Near Earth Asteroids (the ones that come close to the Earth, not the ones in the asteroid belt between Mars and Jupiter). Many scientists …
3. ### physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after …
4. ### physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after …

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after …
6. ### Physics

In the early morning hours of June 14, 2002, the Earth had a remarkably close encounter with an asteroid the size of a small city. The previously unknown asteroid, now designated 2002 MN, remained undetected until three days after …
7. ### Physics

The asteroid belt circles the sun between the orbits of Mars and Jupiter. One asteroid has a period of 10 Earth years. a) What is the asteroid's orbital radius?
8. ### Physics

The Earth has an angular speed of 7.272·10-5 rad/s in its rotation. Find the new angular speed if an asteroid (m = 3.45·1022 kg) hits the Earth while traveling at a speed of 4.41·103 m/s (assume the asteroid is a point mass compared …
9. ### physics

You're heading an international effort to save Earth from an asteroid heading toward us at 11km/s . Your team mounts a rocket on the asteroid and fires it for 10 min, after which the asteroid is moving at 21km/s at 32∘ to its …
10. ### Physics 20

Astronomers launch a satellite to explore a nearby asteroid that has come dangerously close to the earth.The satellite begins orbit around the earth,with an orbital radius 6.85 X 10^3 Km, before being moved to an orbit about the asteroid …

More Similar Questions

Post a New Question