Interesting Questions

Momentum

I’ve just created this question for my undergraduated students that are going to apply for an engineering institute. I’m not quite sure if it’s a nice question, so I’d like to know your opinions or suggestions about it (and yours solutions, of course!)A flying saucer with mass 5m and radius R is at rest and preparing to destroy our beloved Earth. An aircraft is therefore sent to prevent it and shoots a missile with mass m and velocity v1 at the same plane of the flying saucer. The UFO reacts and launches an intercepting missile of mass m and velocity v2 that makes a 30o angle with the direction of the first projectile. If both projectiles meet after a distance h from the launching point of the second missile and then keep moving together, find the minimal value of v2 for which the aircraft will not hit the target.PS.: Ignore friction and gravitational forcesPlease check the attached picture.
Marcos Valle asked

Weightlessness in a satellite

Guion Bluford Experiences Weightlessness on the KC-135 – GPN-2002-000148 (Photo credit: Wikipedia)

Why does an astronaut feel weightless in a space capsule orbiting the earth?

I’ve gotten a key point saying that the space capsule orbiting the earth has a centripetal acceleration, but I cannot figure out why is it related to the question.

Asked Ganondorf Jallida

Answer: The centripetal acceleration is provided by the force of gravity. Since the force of gravity is completely used up in providing the centripetal acceleration to the space capsule, the astronaut feel weightlessness.

Time Paradox

Question: In Michio Kaku’s book Parallel Universes, it addresses the infinite possibility of a “time river” in correlation with Time Travel and its respective paradoxes. The one is question would be the grandfather paradox, in which if one would travel back in time and dispatch their parents his own future would would be “impossible”.

It has been suggested than not unlike a fork in the river, his own sequence of events that portray his future would remain unaffected rather the action would invoke a split or fork in the river to extend a parallel future to which he did not exist. Can you please prescribe further insight to this conundrum and any further literature on this subject would be much appreciated. For reference this is discussed on the last 4-5 pages of Chapter 5 in the book.

Asked by Z King

Is the universe expanding or are we getting smaller?

English: Universe as per Jainism (Photo credit: Wikipedia)

Is the universe expanding or are we getting smaller?

Asked Dany Burton

The Question is left for the readers to answer

Related articles

• What Is the Universe In One Minute