# Black Holes Gre.67

1. Nov 30, 2003

### yxgao

Black Holes Gre.67
67. A black hole is an object whose gravitational field is so strong that even light cannot escape. To what approximate radius would Earth (mass = 5.98 x 10^24

kilograms) have to be compressed in order to become a black hole?
a. 1 nm
b. 1 microm
c. 1 cm
d. 100 m
e. 10 km

the answer is C.

2. Nov 30, 2003

### chroot

Staff Emeritus
$$r_s = \frac{2 G M}{c^2}$$

- Warren

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