사이언스 올제

읽고 생각하는 과학문제

● 3월호 문제 ☞3월호 문제풀이

1. (News, Spaceflight) How much heat per second (W) is emitted by 10 kg of Plutonium 238? The half-life of Pu-238 is 88y and the decay gives a 5.5 MeV alpha particle. You can assume that all of the energy of the alpha particle results in heat.

A. 1 W

B. 30 W

C. 3500 W

D. 6 kW

E. 1 MW

2. (Space Wars, p.78) Estimate the probability that the International Space Station (50m x 50m) in orbit at 200 km will be hit by a cm-sized piece of space junk within the next year.

A. zero

B. 1 %

C. 25 %

D. 60 %

E. 100 %

3. (Quantum Computing, p.62) Using the "grade school method" to multiple two numbers each of n digits, suppose that for n=4 it takes you 20 seconds. This task is "polynomial in n" and goes like the square of n. How long will it take for n=5000 ?

A. 1 day

B. 100 days

C. 1 year

D. 100 years

E. 1 million years

4. One main advantage of a quantum computer is that a small number of particles (e.g. spin-1/2 electrons that can be in two states) can store an enormous amount of information. A computer with 10 such electrons can store how many pieces of information?

A. 5

B. 10

C. 100

D. 1000

E. 1 000 000