Astronomers estimate that a 2

-

km wide asteroid collides with the Earth once every million years. The

collision could pose a threat to life on Earth. (a) Assume a spherical asteroid has a mass of 3200 kg

for

each cubic meter of volume and moves toward the Earth at 15 km/s. How much destructive energy

could be released when it embeds itself in the Earth? (b) For comparison, a nuclear bomb could release

about

. How many such bombs would have to

explode simultaneously to release the

destructive energy of the asteroid collision with Earth? ...?