Why should the emitted neutrons be slowed down in sustainable chain reaction

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.

During the past 150 years in the united states, how did energy consumption compare to population growth

Un conductor circula por una carretera en una velocidad de 90 km/h y b que se enciende la luz amarilla de un semáforo situado una distancia de 150 m. si el semáforo tarda tres segundos en cambiar a rojo el coche frena con una aceleración de 2 m por segundos 2¿ cometer una infracción ese conductor?